Detection device

ABSTRACT

A detection device includes a photodiode, and a thin-film transistor coupled to the photodiode. The thin-film transistor includes a semiconductor layer between a light-blocking layer and the photodiode, and an electrode layer between the semiconductor layer and the photodiode, and the electric layer includes a source electrode and a drain electrode of the thin-film transistor. The source electrode extends to a position facing the light-blocking layer with the semiconductor layer interposed therebetween.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority from Japanese PatentApplication No. 2019-078926 filed on Apr. 17, 2019 and InternationalPatent Application No. PCT/JP2020/016504 filed on Apr. 15, 2020, theentire contents of which are incorporated herein by reference.

BACKGROUND 1. Technical Field

What is disclosed herein relates to a detection device.

2. Description of the Related Art

Optical sensors capable of detecting a fingerprint pattern and/or a veinpattern are known (for example, Japanese Patent Application Laid-openPublication No. 2009-032005).

When a thin-film transistor is used to control output timing of theoptical sensor, light blocking is required to reduce malfunctions thatare caused by a photovoltaic effect of a semiconductor. However, toprovide light-blocking layers on both sides with the semiconductorinterposed therebetween, the number of manufacturing processes increasesonly for forming the light-blocking layers. Therefore, a technique isrequired to restrain such increase in the number of manufacturingprocesses.

For the foregoing reasons, there is a need fora detection device thatcan be provided with a configuration for blocking light to a thin-filmtransistor using fewer manufacturing processes.

SUMMARY

According to an aspect, a detection device includes: a photodiode; and athin-film transistor coupled to the photodiode. The thin-film transistorincludes: a semiconductor layer between a light-blocking layer and thephotodiode; and an electrode layer between the semiconductor layer andthe photodiode, and the electric layer includes a source electrode and adrain electrode of the thin-film transistor. The source electrodeextends to a position facing the light-blocking layer with thesemiconductor layer interposed therebetween.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view illustrating a detection device according to afirst embodiment;

FIG. 2 is a block diagram illustrating a configuration example of thedetection device according to the first embodiment;

FIG. 3 is a circuit diagram illustrating the detection device;

FIG. 4 is a circuit diagram illustrating a plurality of partialdetection areas;

FIG. 5A is an enlarged schematic configuration diagram of a sensor;

FIG. 5B is a Q-Q sectional view of FIG. 5A;

FIG. 6 is a graph schematically illustrating a relation between awavelength and a conversion efficiency of light incident on aphotodiode;

FIG. 7 is a timing waveform diagram illustrating an operation example ofthe detection device;

FIG. 8 is a timing waveform diagram illustrating an operation exampleduring a reading period in FIG. 7;

FIG. 9 is an explanatory diagram for explaining a relation betweendriving of the sensor and lighting operations of light sources, in thedetection device;

FIG. 10 is an explanatory diagram for explaining a relation between thedriving of the sensor and the lighting operations of the light sources,according to a first modification of the first embodiment;

FIG. 11 is a cross sectional view schematically illustrating a relationbetween the sensor and first and second light sources of the detectiondevice according to the first embodiment;

FIG. 12 is another cross sectional view schematically illustrating therelation between the sensor and the first and second light sources ofthe detection device according to the first embodiment;

FIG. 13 is a schematic view illustrating an exemplary positionalrelation between the second light sources, the sensor, and a bloodvessel in a finger;

FIG. 14 is a schematic view illustrating a plurality of positions in thephotodiode that are exemplarily set when a planar detection area formedby a plurality of the photodiodes provided so as to face the finger isviewed in a plan view;

FIG. 15 is a graph illustrating temporal change examples of detectionsignals acquired at the positions illustrated in FIG. 14;

FIG. 16 is a time chart for explaining a relation between apredetermined period and an output from the photodiode identified byfocus processing;

FIG. 17 is a flowchart illustrating an exemplary flow of processing foroutputting pulse wave data in the first embodiment;

FIG. 18 is a schematic diagram for explaining pulse wave dataacquisition control on a group area basis;

FIG. 19 is another schematic diagram for explaining the pulse wave dataacquisition control on a group area basis;

FIG. 20 is an explanatory diagram illustrating examples of averagingprocessing of outputs from the partial detection areas;

FIG. 21 is a flowchart illustrating an exemplary flow of processing foroutputting the pulse wave data in a second embodiment;

FIG. 22 is a flowchart illustrating an exemplary flow of processing foroutputting the pulse wave data in a third embodiment and a fourthembodiment;

FIG. 23 is a flowchart illustrating an exemplary flow of initialprocessing of FIG. 22;

FIG. 24 is a flowchart illustrating an exemplary flow of positionalshift handling processing of FIG. 22 in the third embodiment;

FIG. 25 is a flowchart illustrating an exemplary flow of the positionalshift handling processing of FIG. 22 in a modification of the thirdembodiment;

FIG. 26 is a flowchart illustrating an exemplary flow of the positionalshift handling processing of FIG. 22 in the fourth embodiment;

FIG. 27 is a flowchart illustrating an exemplary flow of the positionalshift handling processing of FIG. 22 in a modification of the fourthembodiment;

FIG. 28 is a schematic view illustrating a main configuration example ofa detection device in a form wearable on a wrist;

FIG. 29 is a schematic view illustrating an example of detection of theblood vessel by the detection device illustrated in FIG. 28;

FIG. 30 is a diagram illustrating a configuration example in which alens is provided between the finger and the sensor;

FIG. 31 is a schematic diagram illustrating a main configuration exampleof a mutual capacitive sensor;

FIG. 32 is a schematic diagram illustrating a main configuration exampleof a self-capacitive sensor;

FIG. 33 is a diagram illustrating an arrangement example of the sensorof the detection device mounted on a bandanna;

FIG. 34 is a diagram illustrating an arrangement example of the sensorof the detection device mounted on clothes; and

FIG. 35 is a diagram illustrating an arrangement example of the sensorof the detection device mounted on an adhesive sheet.

DETAILED DESCRIPTION

The following describes modes (embodiments) for carrying out the presentinvention in detail with reference to the drawings. The presentinvention is not limited to the description of the embodiments givenbelow. Components described below include those easily conceivable bythose skilled in the art or those substantially identical thereto.Moreover, the components described below can be appropriately combined.The disclosure is merely an example, and the present invention naturallyencompasses appropriate modifications easily conceivable by thoseskilled in the art while maintaining the gist of the invention. Tofurther clarify the description, the drawings schematically illustrate,for example, widths, thicknesses, and shapes of various parts ascompared with actual aspects thereof, in some cases. However, they aremerely examples, and interpretation of the present invention is notlimited thereto. The same element as that illustrated in a drawing thathas already been discussed is denoted by the same reference numeralthrough the description and the drawings, and detailed descriptionthereof will not be repeated in some cases where appropriate.

In this disclosure, when an element is described as being “on” anotherelement, the element can be directly on the other element, or there canbe one or more elements between the element and the other element.

First Embodiment

FIG. 1 is a plan view illustrating a detection device according to afirst embodiment. As illustrated in FIG. 1, a detection device 1includes a sensor base member 21, a sensor 10, a gate line drive circuit15, a signal line selection circuit 16, a detection circuit 48, acontrol circuit 122, a power supply circuit 123, a first light sourcebase member 51, a second light source base member 52, at least one firstlight source 61, and at least one second light source 62.

A control board 121 is electrically coupled to the sensor base member 21through a flexible printed circuit board 71. The flexible printedcircuit board 71 is provided with the detection circuit 48. The controlboard 121 is provided with the control circuit 122 and the power supplycircuit 123. The control circuit 122 is, for example, a fieldprogrammable gate array (FPGA). The control circuit 122 supplies controlsignals to the sensor 10, the gate line drive circuit 15, and the signalline selection circuit 16 to control a detection operation of the sensor10. The control circuit 122 supplies control signals to the first lightsources 61 and the second light sources 62 to control to turn on and offthe first light sources 61 and the second light sources 62. The powersupply circuit 123 supplies voltage signals including, for example, asensor power supply signal VDDSNS (refer to FIG. 4) to the sensor 10,the gate line drive circuit 15, and the signal line selection circuit16. The power supply circuit 123 also supplies a power supply voltage tothe first light sources 61 and the second light sources 62.

The sensor base member 21 has a detection area AA and a peripheral areaGA. The detection area AA is an area provided with a plurality ofphotodiodes PD (refer to FIG. 4) included in the sensor 10. Theperipheral area GA is an area between the outer circumference of thedetection area AA and ends of the sensor base member 21 and is an areanot overlapping the photodiodes PD.

The gate line drive circuit 15 and the signal line selection circuit 16are provided in the peripheral area GA. Specifically, the gate linedrive circuit 15 is provided in an area of the peripheral area GAextending along a second direction Dy, and the signal line selectioncircuit 16 is provided in an area of the peripheral area GA extendingalong a first direction Dx and is provided between the sensor 10 and thedetection circuit 48.

The first direction Dx is a direction in a plane parallel to the sensorbase member 21. The second direction Dy is a direction in a planeparallel to the sensor base member 21 and is a direction orthogonal tothe first direction Dx. The second direction Dy may intersect the firstdirection Dx without being orthogonal thereto. A third direction Dz is adirection orthogonal to the first direction Dx and the second directionDy, and is the normal direction of the sensor base member 21.

The first light sources 61 are provided on the first light source basemember 51 and are arranged along the second direction Dy. The secondlight sources 62 are provided on the second light source base member 52and are arranged along the second direction Dy. The first light sourcebase member 51 and the second light source base member 52 areelectrically coupled through terminals 124 and 125, respectively,provided on the control board 121 to the control circuit 122 and thepower supply circuit 123.

For example, inorganic light-emitting diodes (LEDs) or organicelectroluminescent (EL) diodes (organic light-emitting diodes) (OLEDs)are used as the first light sources 61 and the second light sources 62.The first light sources 61 and the second light sources 62 emit firstlight L61 and second light L62 (refer to, for example, FIG. 11),respectively, having wavelengths different from each other. The firstlight L61 and the second light L62 have different maximum emissionwavelengths from each other. The term “maximum emission wavelength”refers to a wavelength that exhibits the maximum emission intensity inan emission spectrum representing a relation between the wavelength andthe emission intensity of each of the first light L61 and the secondlight L62. Hereinafter, when a value of the wavelength is simplymentioned, the mentioned value refers to an assumed maximum emissionwavelength.

The first light L61 emitted from the first light sources 61 is mainlyreflected on a surface of a detection target object, for example, afinger Fg, and enters the sensor 10. Thus, the sensor 10 can detect afingerprint by detecting a shape of asperities of the surface of, forexample, the finger Fg. The second light L62 emitted from the secondlight sources 62 is mainly reflected inside, for example, the finger Fg,or transmitted through, for example, the finger Fg, and enters thesensor 10. Thus, the sensor 10 can detect biological information on theinside, for example, the finger Fg. The biological information is, forexample, a pulse wave, pulsation, and a blood vessel image of the fingerFg or a palm.

As an example, the first light L61 may have a wavelength in a range from520 nm to 600 nm, for example, at approximately 560 nm, and the secondlight L62 may have a wavelength in a range from 780 nm to 900 nm, forexample, at approximately 850 nm. In this case, the first light L61 isblue or green visible light, and the second light L62 is infrared light.The sensor 10 can detect a fingerprint based on the first light L61emitted from the first light sources 61. The second light L62 emittedfrom the second light sources 62 is reflected in the detection targetobject such as the finger Fg, or transmitted through or absorbed by, forexample, the finger Fg, and enters the sensor 10. Thus, the sensor 10can detect the pulse wave and the blood vessel image (vascular pattern)as the biological information on the inside, for example, the finger Fg.

Alternatively, the first light L61 may have a wavelength in a range from600 nm to 700 nm, for example, at approximately 660 nm, and the secondlight L62 may have a wavelength in a range from 780 nm to 900 nm, forexample, at approximately 850 nm. In this case, the sensor 10 can detecta blood oxygen saturation level in addition to the pulsation and theblood vessel image as the biological information based on the firstlight L61 emitted from the first light sources 61 and the second lightL62 emitted from the second light sources 62. In this manner, since thedetection device 1 includes the first light sources 61 and the secondlight sources 62, the detection device 1 can detect the various types ofthe biological information by performing the detection based on thefirst light L61 and the detection based on the second light L62.

The arrangement of the first light sources 61 and the second lightsources 62 illustrated in FIG. 1 is merely an example, and can bechanged as appropriate. For example, the first light sources 61 and thesecond light sources 62 may be arranged on each of the first lightsource base member 51 and the second light source base member 52. Inthis case, a group including the first light sources 61 and a groupincluding the second light sources 62 may be arranged in the seconddirection Dy, or the first light source 61 and the second light source62 may be alternately arranged in the second direction Dy. The number ofthe light source base members provided with the first light sources 61and the second light sources 62 may be one, or three or more.

FIG. 2 is a block diagram illustrating a configuration example of thedetection device according to the first embodiment. As illustrated inFIG. 2, the detection device 1 further includes a detection controller11 and a detector 40. The control circuit 122 includes some or allfunctions of the detection controller 11. The control circuit 122 alsoincludes some or all functions of the detector 40 except those of thedetection circuit 48.

The sensor 10 is an optical sensor including the photodiodes PD servingas photoelectric conversion elements. Each of the photodiodes PDincluded in the sensor 10 outputs an electrical signal corresponding tolight emitted thereto to the signal line selection circuit 16. Thesignal line selection circuit 16 sequentially selects a signal line SGLin response to a selection signal ASW from the detection controller 11.As a result, the electrical signal is output as a detection signal Vdetto the detector 40. The sensor 10 performs the detection in response toa gate drive signal Vgcl supplied from the gate line drive circuit 15.

The detection controller 11 is a circuit that supplies respectivecontrol signals to the gate line drive circuit 15, the signal lineselection circuit 16, and the detector 40 to control operations thereof.The detection controller 11 supplies various control signals including,for example, a start signal STV, a clock signal CK, and a reset signalRST1 to the gate line drive circuit 15. The detection controller 11 alsosupplies various control signals including, for example, the selectionsignal ASW to the signal line selection circuit 16. The detectioncontroller 11 also supplies various control signals to the first lightsources 61 and the second light sources 62 to control to turn on and offthe first light sources 61 and the second light sources 62.

The gate line drive circuit 15 is a circuit that drives a plurality ofgate lines GCL (refer to FIG. 3) based on the various control signals.The gate line drive circuit 15 sequentially or simultaneously selectsthe gate lines GCL and supplies the gate drive signals Vgcl to theselected gate lines GCL. Through this operation, the gate line drivecircuit 15 selects the photodiodes PD coupled to the gate lines GCL.

The signal line selection circuit 16 is a switch circuit thatsequentially or simultaneously selects a plurality of signal lines SGL(refer to FIG. 3). The signal line selection circuit 16 is, for example,a multiplexer. The signal line selection circuit 16 couples the selectedsignal lines SGL to the detection circuit 48 based on the selectionsignal ASW supplied from the detection controller 11. Through thisoperation, the signal line selection circuit 16 outputs the detectionsignal Vdet of each of the photodiodes PD to the detector 40.

The detector 40 includes the detection circuit 48, a signal processor44, a coordinate extractor 45, a storage 46, a detection timingcontroller 47, an image processor 49, and an output processor 50. Basedon a control signal supplied from the detection controller 11, thedetection timing controller 47 controls the detection circuit 48, thesignal processor 44, the coordinate extractor 45, and the imageprocessor 49 so as to operate in synchronization with one another.

The detection circuit 48 is, for example, an analog front end (AFE)circuit. The detection circuit 48 is, for example, a signal processingcircuit having functions of a detection signal amplifier 42 and ananalog-to-digital (A/D) converter 43. The detection signal amplifier 42amplifies the detection signal Vdet. The A/D converter 43 converts ananalog signal output from the detection signal amplifier 42 into adigital signal.

The signal processor 44 is a logic circuit that detects a predeterminedphysical quantity received by the sensor 10 based on an output signal ofthe detection circuit 48. When the finger Fg is in contact with or inproximity to the detection area AA, the signal processor 44 can detectthe asperities on the surface of the finger Fg or the palm based on thesignal from the detection circuit 48. The signal processor 44 can alsodetect the biological information based on the signal from the detectioncircuit 48. The biological information is, for example, the blood vesselimage, a pulse wave, the pulsation, and/or the blood oxygen saturationlevel of the finger Fg or the palm.

In the case of obtaining the human blood oxygen saturation level, forexample, 660 nm (the range is from 500 nm to 700 nm) is employed as thefirst light L61, and approximately 850 nm (the range is from 800 nm to930 nm) is employed as the second light L62. Since the amount of lightabsorption changes with an amount of oxygen taken up by hemoglobin, thephotodiode PD detects an amount of light obtained by subtracting theamount of light absorbed by the blood (hemoglobin) from that of each ofthe first light L61 and the second light L62 that have been emitted.Most of the oxygen in the blood is reversibly bound to hemoglobin in redblood cells, and a small portion of the oxygen is dissolved in bloodplasma. More specifically, the value of percentage of oxygen withrespect to an allowable amount thereof in the blood as a whole is calledthe oxygen saturation level (SpO₂). The blood oxygen saturation levelcan be calculated from the amount of light obtained by subtracting theamount of light absorbed by the blood (hemoglobin) from that of thelight emitted at the two wavelengths of the first light L61 and thesecond light L62.

The signal processor 44 may acquire the detection signals Vdet(biological information) simultaneously detected by the photodiodes PD,and average the detection signals Vdet. In this case, the detector 40can perform the stable detection by reducing a measurement error causedby noise or a relative displacement between the detection target objectsuch as the finger Fg and the sensor 10.

The storage 46 temporarily stores therein a signal calculated by thesignal processor 44. The storage 46 may be, for example, a random accessmemory (RAM) or a register circuit.

The coordinate extractor 45 is a logic circuit that obtains, when thecontact or the proximity of the finger is detected by the signalprocessor 44, detection coordinates of the asperities on the surface of,for example, the finger. The coordinate extractor 45 is also a logiccircuit that obtains detected coordinates of blood vessels of the fingerFg or the palm. The image processor 49 combines the detection signalsVdet output from the respective photodiodes PD of the sensor 10 togenerate two-dimensional information representing the shape of theasperities on the surface of, for example, the finger Fg andtwo-dimensional information representing a shape of the blood vessels ofthe finger Fg or the palm. The coordinate extractor 45 and the imageprocessor 49 may be omitted.

The output processor 50 serves as a processor for performing processingbased on the output from the photodiodes PD. Specifically, the outputprocessor 50 of the embodiment outputs at least a sensor output Voincluding at least pulse wave data based on the detection signal Vdetacquired through the signal processor 44. In the embodiment, the signalprocessor 44 outputs data indicating a variation (amplitude) in outputof the detection signal Vdet of each of the photodiodes PD (to bedescribed later), and the output processor 50 determines which output isto be employed as the sensor output Vo. However, the signal processor 44or the output processor 50 may perform both the above-describedoperations. The output processor 50 may include, for example, thedetected coordinates obtained by the coordinate extractor 45 and thetwo-dimensional information generated by the image processor 49 in thesensor output Vo. The function of the output processor 50 may beintegrated in another component (for example, the image processor 49).

When the detection device for, for example, the pulse wave is mounted ona human body, noise is also detected associated with, for example,breathing, a change in attitude of the human body, and/or motion of thehuman body. Therefore, the signal processor 44 may be provided with anoise filter as required. The noise generated by the breathing and/orthe change in attitude has frequency components of, for example, 1 Hz orlower, which are sufficiently lower than frequency components of thepulse wave. Therefore, the noise can be removed by using a band-passfilter as the noise filter. The band-pass filter may be provided, forexample, in a detection signal amplifier 42. The frequency components ofthe noise generated by the motion of the human body are, for example,from several hertz to 100 hertz, and may overlap the frequencycomponents of the pulse wave. In this case, however, the frequency isnot constant and has a frequency fluctuation. Therefore, a noise filteris used that removes noise the frequencies of which have fluctuationcomponents. As an example of a method for removing the frequencieshaving fluctuation components (first method for removing fluctuationcomponents), a property may be used that a time lag of a peak value ofthe pulse wave occurs depending on the place of measurement of the humanbody. That is, the pulse wave has a time lag depending on the place ofmeasurement of the human body, while the noise generated by the motionof the human body or the like has no time lag or a time lag smaller thanthat of the pulse wave. Therefore, the pulse wave is measured in atleast two different places, and if peak values measured in the differentplaces have occurred within a predetermined time, the pulse wave isremoved as noise. Even in this case, a case can be considered where thewaveform caused by noise accidentally overlaps the waveform caused bythe pulse wave. However, in this case, the two waveforms overlap eachother at only one place of the different places. Therefore, the waveformcaused by noise can be distinguished from the waveform caused by thepulse wave. For example, the signal processor 44 can perform thisprocessing. As another example of the method for removing thefrequencies having fluctuation components (second method for removingfluctuation components), the signal processor 44 removes frequencycomponents having different phases. In this case, for example, ashort-time Fourier transform may be performed to remove the fluctuationcomponents, and then, an inverse Fourier transform may be performed.Moreover, a commercial frequency power supply (50 Hz or 60 Hz) alsoserves as a noise source. However, in this case as well, in the samemanner as the noise generated by the motion of the human body or otherfactors, the peak values measured at the different places have no timelag therebetween or a time lag therebetween smaller than that of thepulse wave. Therefore, the noise can be removed using the same method asthe above-described first method for removing fluctuation components.Alternatively, the noise generated by the commercial frequency powersupply may be removed by providing a shield on a surface on the oppositeside of a detection surface of a detecting element.

The following describes a circuit configuration example of the detectiondevice 1. FIG. 3 is a circuit diagram illustrating the detection device.FIG. 4 is a circuit diagram illustrating a plurality of partialdetection areas. FIG. 4 also illustrates a circuit configuration of thedetection circuit 48.

As illustrated in FIG. 3, the sensor 10 has a plurality of partialdetection areas PAA arranged in a matrix having a row-columnconfiguration. Each of the partial detection areas PAA is provided withthe photodiode PD.

The gate lines GCL extend in the first direction Dx, and are coupled tothe partial detection areas PAA arranged in the first direction Dx. Aplurality of gate lines GCL(1), GCL(2), . . . , GCL(8) are arranged inthe second direction Dy, and are each coupled to the gate line drivecircuit 15. In the following description, the gate lines GCL(1), GCL(2),. . . , GCL(8) will each be simply referred to as the gate line GCL whenthey need not be distinguished from one another. For ease ofunderstanding of the description, FIG. 3 illustrates eight gate linesGCL. However, this is merely an example, and M gate lines GCL (where Mis eight or larger, and is, for example, 256) may be arranged.

The signal lines SGL extend in the second direction Dy and are coupledto the photodiodes PD of the partial detection areas PAA arranged in thesecond direction Dy. A plurality of signal lines SGL(1), SGL(2), . . . ,SGL(12) are arranged in the first direction Dx and are each coupled tothe signal line selection circuit 16 and a reset circuit 17. In thefollowing description, the signal lines SGL(1), SGL(2), . . . , SGL(12)will each be simply referred to as the signal line SGL when need not bedistinguished from one another.

For ease of understanding of the description, 12 signal lines SGL areillustrated. However, this is merely an example, and N signal lines SGL(where N is 12 or larger, and is, for example, 252) may be arranged. Theresolution of the sensor is, for example, 508 dots per inch (dpi), andthe number of cells is 252×256. In FIG. 3, the sensor 10 is providedbetween the signal line selection circuit 16 and the reset circuit 17.The configuration is not limited thereto. The signal line selectioncircuit 16 and the reset circuit 17 may be coupled to ends of the signallines SGL in the same direction. One sensor has an area of substantially50×50 μm², for example. The detection area AA has an area of, forexample, 12.6×12.8 mm².

The gate line drive circuit 15 receives the various control signals suchas the start signal STV, the clock signal CK, and the reset signal RST1from the control circuit 122 (refer to FIG. 1). The gate line drivecircuit 15 sequentially selects the gate lines GCL(1), GCL(2), . . . ,GCL(8) in a time-division manner based on the various control signals.The gate line drive circuit 15 supplies the gate drive signal Vgcl tothe selected one of the gate lines GCL. This operation supplies the gatedrive signal Vgcl to a plurality of first switching elements Tr coupledto the gate line GCL, and corresponding ones of the partial detectionareas PAA arranged in the first direction Dx are selected as detectiontargets.

The gate line drive circuit 15 may perform different driving for each ofdetection modes including the detection of a fingerprint and thedetection of different items of the biological information (such as thepulse wave, the pulsation, the blood vessel image, and the blood oxygensaturation level). For example, the gate line drive circuit 15 may drivemore than one gate line GCL collectively.

Specifically, the gate line drive circuit 15 may simultaneously select apredetermined number of the gate lines GCL from among the gate linesGCL(1), GCL(2), . . . , GCL(8) based on the control signals. Forexample, the gate line drive circuit 15 simultaneously selects six gatelines GCL(1) to GCL(6) and supplies thereto the gate drive signals Vgcl.The gate line drive circuit 15 supplies the gate drive signals Vgclthrough the selected six gate lines GCL to the first switching elementsTr. Through this operation, group areas PAG1 and PAG2 each includingmore than one partial detection area PAA arranged in the first directionDx and the second direction Dy are selected as the respective detectiontargets. The gate line drive circuit 15 drives the predetermined numberof the gate lines GCL collectively, and sequentially supplies the gatedrive signals Vgcl to the gate lines GCL in units of the predeterminednumber of the gate lines GCL. Hereinafter, when positions of differentgroup areas such as the group areas PAG1 and PAG2 are not distinguishedfrom each other, each of the group areas will be called “group areaPAG”.

The signal line selection circuit 16 includes a plurality of selectionsignal lines Lsel, a plurality of output signal lines Lout, and thirdswitching elements TrS. The third switching elements TrS are providedcorrespondingly to the signal lines SGL. Six signal lines SGL(1),SGL(2), . . . , SGL(6) are coupled to a common output signal line Lout1.Six signal lines SGL(7), SGL(8), . . . , SGL(12) are coupled to a commonoutput signal line Lout2. The output signal lines Lout1 and Lout2 areeach coupled to the detection circuit 48.

The signal lines SGL(1), SGL(2), . . . , SGL(6) are grouped into a firstsignal line block, and the signal lines SGL(7), SGL(8), . . . , SGL(12)are grouped into a second signal line block. The selection signal linesLsel are coupled to the gates of the third switching elements TrSincluded in one of the signal line blocks, respectively. One of theselection signal lines Lsel is coupled to the gates of the thirdswitching elements TrS in the signal line blocks.

Specifically, selection signal lines Lsel1, Lsel2, . . . , Lsel6 arecoupled to the third switching elements TrS corresponding to the signallines SGL(1), SGL(2), . . . , SGL(6), respectively. The selection signalline Lsel1 is coupled to the third switching element TrS correspondingto the signal line SGL(1) and the third switching element TrScorresponding to the signal line SGL(7). The selection signal line Lsel2is coupled to the third switching element TrS corresponding to thesignal line SGL(2) and the third switching element TrS corresponding tothe signal line SGL(8).

The control circuit 122 (refer to FIG. 1) sequentially supplies theselection signal ASW to the selection signal lines Lsel. Through theoperations of the third switching elements TrS, the signal lineselection circuit 16 sequentially selects the signal lines SGL in one ofthe signal line blocks in a time-division manner. The signal lineselection circuit 16 selects one of the signal lines SGL in each of thesignal line blocks. With the above-described configuration, thedetection device 1 can reduce the number of integrated circuits (ICs)including the detection circuit 48 or the number of terminals of theICs.

The signal line selection circuit 16 may couple more than one signalline SGL to the detection circuit 48 collectively. Specifically, thecontrol circuit 122 (refer to FIG. 1) simultaneously supplies theselection signal ASW to the selection signal lines Lsel. With thisoperation, the signal line selection circuit 16 selects, by theoperations of the third switching elements TrS, the signal lines SGL(for example, six signal lines SGL) in one of the signal line blocks,and couples the signal lines SGL to the detection circuit 48. As aresult, signals detected in each group area PAG are output to thedetection circuit 48. In this case, signals from the partial detectionareas PAA (photodiodes PD) in each group area PAG are put together andoutput to the detection circuit 48.

By the operations of the gate line drive circuit 15 and the signal lineselection circuit 16, the detection is performed for each group areaPAG. As a result, the intensity of the detection signal Vdet obtained byone time of detection increases, so that the sensor sensitivity can beimproved. In addition, time required for the detection can be reduced.Consequently, the detection device 1 can repeatedly perform thedetection in a short time, and thus, can improve a signal-to-noise (S/N)ratio, and can accurately detect a change in the biological informationwith time, such as the pulse wave.

As illustrated in FIG. 3, the reset circuit 17 includes a referencesignal line Lvr, a reset signal line Lrst, and fourth switching elementsTrR. The fourth switching elements TrR are provided correspondingly tothe signal lines SGL. The reference signal line Lvr is coupled to eitherthe sources or the drains of the fourth switching elements TrR. Thereset signal line Lrst is coupled to the gates of the fourth switchingelements TrR.

The control circuit 122 supplies a reset signal RST2 to the reset signalline Lrst. This operation turns on the fourth switching elements TrR toelectrically couple the signal lines SGL to the reference signal lineLvr. The power supply circuit 123 supplies a reference signal COM to thereference signal line Lvr. This operation supplies the reference signalCOM to a capacitive element Ca (refer to FIG. 4) included in each of thepartial detection areas PAA.

As illustrated in FIG. 4, each of the partial detection areas PAAincludes the photodiode PD, the capacitive element Ca, and the firstswitching element Tr. FIG. 4 illustrates two gate lines GCL(m) andGCL(m+1) arranged in the second direction Dy among the gate lines GCLand illustrates two signal lines SGL(n) and SGL(n+1) arranged in thefirst direction Dx among the signal lines SGL. The partial detectionarea PAA is an area surrounded by the gate lines GCL and the signallines SGL. Each of the first switching elements Tr is providedcorrespondingly to each of the photodiodes PD. The first switchingelement Tr includes a thin-film transistor, and in this example,includes an n-channel metal oxide semiconductor (MOS) thin-filmtransistor (TFT).

The gates of the first switching elements Tr belonging to the partialdetection areas PAA arranged in the first direction Dx are coupled tothe gate line GCL. The sources of the first switching elements Trbelonging to the partial detection areas PAA arranged in the seconddirection Dy are coupled to the signal line SGL. The drain of the firstswitching element Tr is coupled to the cathode of the photodiode PD andthe capacitive element Ca.

The anode of the photodiode PD is supplied with the sensor power supplysignal VDDSNS from the power supply circuit 123. The signal line SGL andthe capacitive element Ca are supplied with the reference signal COMthat serves as an initial potential of the signal line SGL and thecapacitive element Ca from the power supply circuit 123.

When the partial detection area PAA is irradiated with light, a currentcorresponding to an amount of light flows through the photodiode PD. Asa result, an electrical charge is stored in the capacitive element Ca.After the first switching element Tr is turned on, a currentcorresponding to the electrical charge stored in the capacitive elementCa flows through the signal line SGL. The signal line SGL is coupled tothe detection circuit 48 through a corresponding one of the thirdswitching elements TrS of the signal line selection circuit 16. Thus,the detection device 1 can detect a signal corresponding to the amountof the light irradiating the photodiode PD in each of the partialdetection areas PAA or signals corresponding to the amounts of the lightirradiating the photodiodes PD in each group area PAG.

During a reading period Pdet (refer to FIG. 7), a switch SSW of thedetection circuit 48 is turned on, and the detection circuit 48 iscoupled to the signal lines SGL. The detection signal amplifier 42 ofthe detection circuit 48 converts a variation of a current supplied fromthe signal lines SGL into a variation of a voltage, and amplifies theresult. A reference potential (Vref) having a fixed potential issupplied to a non-inverting input portion (+) of the detection signalamplifier 42, and the signal lines SGL are coupled to an inverting inputportion (−) of the detection signal amplifier 42. In the firstembodiment, the same signal as the reference signal COM is supplied as areference potential (Vref). The detection signal amplifier 42 includes acapacitive element Cb and a reset switch RSW. During a reset period Prst(refer to FIG. 7), the reset switch RSW is turned on, and an electricalcharge of the capacitive element Cb is reset.

The following describes an outline of a manufacturing method of thesensor 10 and a process for forming the photodiode PD (organicphotodiode (OPD) forming process). FIG. 5A is an enlarged schematicconfiguration diagram of the sensor 10. FIG. 5B is a Q-Q sectional viewof FIG. 5A.

Outline of Manufacturing Method

The outline of the manufacturing method of the sensor 10 will bedescribed. A backplane BP including low-temperature polysilicon (LTPS)22 is formed on an undercoat 26, a light-blocking layer 27, and aninsulator that are stacked on polyimide 25 formed as a film on thesensor base member 21. The thickness of the polyimide 25 is, forexample, 10 μm. A device for forming the backplane BP is separated fromthe sensor base member using a laser lift-off (LLO) technique after allprocesses for forming the backplane BP are completed. The backplane BPserves as the first switching elements Tr. While in the presentembodiment, the LTPS 22 is employed as a semiconductor layer, thesemiconductor layer is not limited thereto and may be formed of anothersemiconductor such as amorphous silicon.

Each of the first switching elements Tr includes a double-gate TFT inwhich two n-channel MOS (NMOS) transistors are coupled. The NMOS has,for example, a channel length of 4.5 μm, a channel width of 2.5 μm, anda mobility of approximately 40 to 70 cm²/Vs. To form the TFT of theLTPS, first, four materials of silicon monoxide (SiO), silicon nitride(SiN), SiO, and amorphous silicon (a-Si) are used to form a film, andthen, a-Si is annealed by an excimer laser to be crystallized to formpolysilicon. A circuit of a surrounding driver portion is formed of acomplementary MOS (CMOS) circuit including a p-channel MOS (PMOS)transistor and an NMOS transistor. The PMOS transistor has, for example,a channel length of 4.5 μm, a channel width of 3.5 μm, and a mobility ofapproximately 40 to 70 cm²/Vs. The NMOS transistor has, for example, achannel length of 4.5 μm, a channel width of 2.5 μm, and a mobility ofapproximately 40 to 70 cm²/Vs in the same manner as described above.After the polysilicon is formed, electrodes of the PMOS and the NMOS areformed by being doped with boron (B) and phosphorus (P).

Then, SiO is formed as an insulating film 23 a, and molybdenum-tungstenalloy (MoW) is formed into films as two gate electrodes GA and GB of thedouble-gate TFT. The thickness of the insulating film 23 a is, forexample, 70 nm. The thickness of MoW for forming the gate electrodes GAand GB is, for example, 250 nm.

After the MoW films are formed, an intermediate film 23 b is formed, andan electrode layer 28 for forming a source electrode 28 a and a drainelectrode 28 b is formed as a film. The electrode layer 28 is, forexample, of an aluminum alloy. A via V1 and a via V2 are formed by dryetching that are for coupling the source electrode 28 a and the drainelectrode 28 b to the electrodes of the PMOS and the NMOS of the LTPS 22that is formed by the doping. The insulating film 23 a and theintermediate film 23 b serve as an insulating layer 23 that isolates thegate electrodes GA and GB serving as the gate line GCL from the LTPS 22and the electrode layer 28.

The thus formed backplane BP includes the LTPS 22 stacked on thephotodiode PD side of the light-blocking layer 27, and the electrodelayer 28 that is stacked between the LTPS 22 and the photodiode PD andin which the source electrode 28 a and the drain electrode 28 b of thefirst switching element Tr are formed. The source electrode 28 a extendsto a position facing the light-blocking layer 27 with the LTPS 22interposed therebetween. That is, the LTPS 22 is provided between thelight-blocking layer 27 and the photodiode PD, and the electrode layer28 is provided between the LTPS 22 and the photodiode PD. The electrodelayer 28 includes the source electrode 28 a and the drain electrode 28 bof the first switching element Tr.

After the backplane BP is manufactured, a smooth layer 29 having athickness of 2 μm is formed to form a layer of an organic photodetectoron top of the backplane BP. Although not illustrated, a sealing film isfurther formed on the smooth layer 29. A via V3 for coupling thebackplane BP to the photodiode PD is formed by etching.

Then, an organic photodiode (OPD) having an air-stable invertedstructure is formed as the photodiode PD on top of the backplane BP. Amaterial having sensitivity to near-infrared light (for example, lighthaving a wavelength of 850 nm) is used as an active layer 31 of thephotodiode PD of the sensor 10 serving as an organic sensor. Indium tinoxide (ITO) is used as a cathode electrode 35 serving as a transparentelectrode, which is coupled to the backplane BP through the via V3.Furthermore, although not illustrated, a zinc oxide (ZnO) layer 35 a isformed on a surface of ITO to adjust the work function of the electrode.

For the organic photodiode, two different devices are produced usingdifferent types of organic semiconductor materials as active layers.Specifically, as the different types of organic semiconductor materials,two types of materials are used, one being PMDPP3T(poly[[2,5-bis(2-hexyldecyl)-2,3,5,6-tetrahydro-3,6-dioxopyrrolo[3,4-c]pyrrole-1,4-diyl]-alt-[3′,3″-dimethyl-2,2′:5′,2″-terthiophene]-5,5″-diyl]),and the other being STD-001 (Sumitomo Chemical Co., Ltd.). A bulkheterostructure is formed by mixing each of the materials with[6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM), and forming themixture into a film. Furthermore, a polythiophene-based conductivepolymer (PEDOT:PSS) and silver (Ag) are formed into a film as an anodeelectrode 34. Although not illustrated, the organic photodiode is sealedwith parylene having a thickness of 1 μm, and on top of the organicphotodiode, chromium and gold (Cr/Au) are formed into a film as acontact pad for coupling to a flexible substrate on which an analogfront end (AFE) is mounted.

Although parylene is used as the sealing film, silicon dioxide (SiO₂) orsilicon oxynitride (SiON) may be used instead. Although PEDOT:PSS isstacked to 10 nm and Ag is stacked to 80 nm as the anode electrode 34,the range of the film thickness may be from 10 nm to 30 nm forPEDOT:PSS, and from 10 nm to 100 nm for Ag. For example, a molybdenumoxide (MoOx) can be used as an alternative material for PEDOT:PSS. Forexample, aluminum (Al) or gold (Au) can be used as an alternativematerial for Ag. Although ZnO is formed on ITO of the cathode electrode35, a polymer such as polyethylenimine (PEI) or ethoxylated PEI (PEIE)may be formed on ITO.

OPD Forming Process

A surface of the chip is subjected to an O₂ plasma treatment under thecondition of 300 W for 10 seconds. Then, the ZnO layer is formed as afilm under the spin-coating condition of 5000 rpm for 30 seconds and isannealed at 180° C. for 30 minutes. A PMDPP3T:PCBM solution or aSTD-001:PCBM solution is spin-coated as an organic layer on the surfaceof ZnO at 250 rpm for 4 minutes. Then, a solution obtained by dilutingPEDOT:PSS (for example, Al4083) with isopropyl alcohol (IPA) to (3:17)under a nitrogen atmosphere is filtered through a polyvinylidenefluoride (PVDF) filter of 0.45 μm, and then, is formed into a film usingthe spin-coating method under the condition of 2000 rpm for 30 seconds(sec). After the film formation, annealing is performed at 80° C. for 5minutes (min) under the nitrogen atmosphere. Finally, silver isvacuum-deposited to 80 nm as the anode electrode 34. After the device iscompleted, parylene is formed into a film of 1 μm as the sealing filmusing a chemical vapor deposition (CVD) method, and Cr/Au isvacuum-deposited as the contact pad.

The photodiode PD formed by such a forming process includes the activelayer 31 serving as an organic material having a photovoltaic effect,the cathode electrode 35 provided on a backplane BP side of the activelayer 31, and the anode electrode 34 provided on an opposite side of theactive layer 31 from the cathode electrode 35. The layer of the activelayer 31 and the layer of the anode electrode 34 are continuous, along adetection surface of the sensor 10 provided so as to be capable ofdetecting the light, over the cathode electrodes 35 of the photodiodesPD (refer to FIGS. 3 and 4) arranged along the detection surface of thesensor 10 (refer to FIG. 5B). That is, the cathode electrode 35 isprovided independently for each of the photodiodes PD, and the activelayer 31 and the anode electrode 34 are continuous over the entiredetection area AA.

FIG. 6 is a graph schematically illustrating a relation between thewavelength and a conversion efficiency of light incident on thephotodiode. The horizontal axis of the graph illustrated in FIG. 6represents the wavelength of the light incident on the photodiode PD,and the vertical axis of the graph represents an external quantumefficiency of the photodiode PD. The external quantum efficiency isexpressed as a ratio between the number of photons of the light incidenton the photodiode PD and a current that flows from the photodiode PD tothe external detection circuit 48.

As illustrated in FIG. 6, the photodiode PD has an excellent efficiencyin a wavelength range from approximately 300 nm to approximately 1000nm. That is, the photodiode PD has a sensitivity for wavelengths of boththe first light L61 emitted from the first light sources 61 and thesecond light L62 emitted from the second light sources 62. Therefore,each of the photodiodes PD can detect a plurality of beams of lighthaving different wavelengths.

The following describes an operation example of the detection device 1.FIG. 7 is a timing waveform diagram illustrating the operation exampleof the detection device. As illustrated in FIG. 7, the detection device1 has the reset period Prst, an effective exposure period Pex, and thereading period Pdet. The power supply circuit 123 supplies the sensorpower supply signal VDDSNS to the anode of the photodiode PD over thereset period Prst, the effective exposure period Pex, and the readingperiod Pdet. The sensor power supply signal VDDSNS is a signal forapplying a reverse bias between the anode and the cathode of thephotodiode PD. For example, the reference signal COM of substantially0.75 V is applied to the cathode of the photodiode PD, and the sensorpower supply signal VDDSNS of substantially −1.25 V is applied to theanode of the photodiode PD. As a result, a reverse bias of substantially2.0 V is applied between the anode and the cathode. At the time ofdetection of a wavelength of 850 nm, the reverse bias of 2 V is appliedto the photodiode PD so as to obtain a high sensitivity of 0.5 A/W to0.7 A/W, preferably approximately 0.57 A/W. The followingcharacteristics of the photodiode are used: the dark current density is1.0×10⁻⁷ A/cm² when the reverse bias of 2 V is applied, and thephotocurrent density is 1.2×10⁻³ A/cm² when light having an output ofsubstantially 2.9 mW/cm² and a wavelength of 850 nm is detected. Theexternal quantum efficiency (EQE) is approximately 1.0 when the reversebias of 2 V is applied at the time when the photodiode is irradiatedwith the light having a wavelength of 850 nm. The control circuit 122sets the reset signal RST2 to “H”, and then, supplies the start signalSTV and the clock signal CK to the gate line drive circuit 15 to startthe reset period Prst. During the reset period Prst, the control circuit122 supplies the reference signal COM to the reset circuit 17, and usesthe reset signal RST2 to turn on the fourth switching elements TrR forsupplying a reset voltage. This operation supplies the reference signalsCOM as the reset voltage to the signal lines SGL. The reference signalCOM is set to, for example, 0.75 V.

During the reset period Prst, the gate line drive circuit 15sequentially selects each of the gate lines GCL based on the startsignal STV, the clock signal CK, and the reset signal RST1. The gateline drive circuit 15 sequentially supplies the gate drive signals Vgcl{Vgcl(1) to Vgcl(M)} to the gate lines GCL. The gate drive signal Vgclhas a pulsed waveform having a power supply voltage VDD serving as ahigh-level voltage and a power supply voltage VSS serving as a low-levelvoltage. In FIG. 7, M gate lines GCL (where M is, for example, 256) areprovided, and the gate drive signals Vgcl(1) . . . , Vgcl(M) aresequentially supplied to the respective gate lines GCL. Thus, the firstswitching elements Tr are sequentially brought into a conducting stateand supplied with the reset voltage on a row-by-row basis. For example,a voltage of 0.75 V of the reference signal COM is supplied as the resetvoltage.

Thus, during the reset period Prst, the capacitive elements Ca of allthe partial detection areas PAA are sequentially electrically coupled tothe signal lines SGL, and are supplied with the reference signal COM. Asa result, the electrical charges stored in the capacitance of thecapacitive elements Ca are reset. The capacitance of the capacitiveelements Ca of some of the partial detection areas PAA can be reset bypartially selecting the gate lines and the signal lines SGL.

Examples of the exposure timing control method include a control methodof exposure during scanning time of gate line and a full-time controlmethod of exposure. In the control method of exposure during scanningtime of gate line, the gate drive signals {Vgcl(1) to Vgcl(M)} aresequentially supplied to all the gate lines GCL coupled to thephotodiodes PD serving as the detection targets, and all the photodiodesPD serving as the detection targets are supplied with the reset voltage.Then, after all the gate lines GCL coupled to the photodiodes PD servingas the detection targets are set to a low voltage (the first switchingelements Tr are turned off), the exposure starts, whereby the exposureis performed during the effective exposure period Pex. After theexposure ends, the gate drive signals {Vgcl(1) to Vgcl(M)} aresequentially supplied to the gate lines GCL coupled to the photodiodesPD serving as the detection targets as described above, and reading isperformed during the reading period Pdet. In the full-time controlmethod of exposure, control for performing the exposure can also beperformed during the reset period Prst and the reading period Pdet(full-time exposure control). In this case, the effective exposureperiod Pex(1) starts after the gate drive signal Vgcl(M) is supplied tothe gate line GCL. The term “effective exposure periods Pex{(1), . . . ,(M)}” refers to a period during which the capacitive elements Ca arecharged from the photodiodes PD. The start timing and the end timing ofthe actual effective exposure periods Pex(1), . . . , Pex(M) aredifferent among the partial detection areas PAA corresponding to thegate lines GCL. Each of the effective exposure periods Pex(1), . . . ,Pex(M) starts when the gate drive signal Vgcl changes from the powersupply voltage VDD serving as the high-level voltage to the power supplyvoltage VSS serving as the low-level voltage during the reset periodPrst. Each of the effective exposure periods Pex(1), . . . , Pex(M) endswhen the gate drive signal Vgcl changes from the power supply voltageVSS to the power supply voltage VDD during the reading period Pdet. Thelengths of the exposure time of the effective exposure periods Pex(1), .. . , Pex(M) are equal.

In the control method of exposure during scanning time of gate line, acurrent flows corresponding to the light irradiating the photodiode PDin each of the partial detection areas PAA during the effective exposureperiod Pex. As a result, an electrical charge is stored in each of thecapacitive elements Ca.

At a time before the reading period Pdet starts, the control circuit 122sets the reset signal RST2 to a low-level voltage. This operation stopsoperation of the reset circuit 17. The reset signal may be set to ahigh-level voltage only during the reset period Prst. During the readingperiod Pdet, the gate line drive circuit 15 sequentially supplies thegate drive signals Vgcl(1), Vgcl(M) to the gate lines GCL in the samemanner as during the reset period Prst.

Specifically, the gate line drive circuit 15 supplies the gate drivesignal Vgcl(1) at the high-level voltage (power supply voltage VDD) tothe gate line GCL(1) during a period V(1). The control circuit 122sequentially supplies the selection signals ASW1, . . . , ASW6 to thesignal line selection circuit 16 during a period in which the gate drivesignal Vgcl(1) is at the high-level voltage (power supply voltage VDD).This operation sequentially or simultaneously couples the signal linesSGL of the partial detection areas PAA selected by the gate drive signalVgcl(1) to the detection circuit 48. As a result, the detection signalVdet for each of the partial detection areas PAA is supplied to thedetection circuit 48. A time of, for example, approximately 20 μs(substantially 20 μs) elapses from when the gate drive signal Vgcl(1) isset to the high level to when the first selection signal ASW1 starts tobe supplied, and a time of, for example, approximately 60 μs(substantially 60 μs) elapses while each of the selection signals ASW1,. . . , ASW6 is supplied. Such a high-speed response can be achieved byusing thin-film transistors (TFTs) made using low-temperaturepolysilicon (LTPS) having mobility of substantially 40 cm²/Vs.

In the same manner, the gate line drive circuit 15 supplies the gatedrive signals Vgcl(2), . . . , Vgcl(M−1), Vgcl(M) at the high-levelvoltage to gate lines GCL(2), . . . , GCL(M−1), GCL(M) during periodsV(2), . . . , V(M−1), V(M), respectively. That is, the gate line drivecircuit 15 supplies the gate drive signal Vgcl to the gate line GCLduring each of the periods V(1), V(2), . . . , V(M−1), V(M). The signalline selection circuit 16 sequentially selects each of the signal linesSGL based on the selection signal ASW in each period in which the gatedrive signal Vgcl is set to the high-level voltage. The signal lineselection circuit 16 sequentially couples each of the signal lines SGLto one detection circuit 48. Thus, the detection device 1 can output thedetection signals Vdet of all the partial detection areas PAA to thedetection circuit 48 during the reading period Pdet.

FIG. 8 is a timing waveform diagram illustrating an operation exampleduring a drive period of one of the gate lines included in a readingperiod Readout in FIG. 7. With reference to FIG. 8, the followingdescribes the operation example during the supply period Readout of oneof the gate drive signals Vgcl(j) in FIG. 7. In FIG. 7, the referencenumeral of the supply period “Readout” is assigned to the first gatedrive signal Vgcl(1), and the same applies to the other gate drivesignals Vgcl(2) . . . , Vgcl(M). The index j is any one of the naturalnumbers 1 to M.

As illustrated in FIGS. 8 and 4, an output (V_(out)) of each of thethird switching elements TrS has been reset to the reference potential(Vref) in advance. The reference potential (Vref) serves as a resetvoltage, and is set to, for example, 0.75 V. Then, the gate drive signalVgcl(j) is set to a high level, and the first switching elements Tr of acorresponding row are turned on. Thus, each of the signal lines SGL ofeach row is set to a voltage corresponding to the electrical chargestored in the capacitor (capacitive element Ca) of the partial detectionarea PAA. After a period t1 elapses from a rise of the gate drive signalVgcl(j), a period t2 starts in which the selection signal ASW(k) is setto a high level. After the selection signal ASW(k) is set to the highlevel and the third switching element TrS is turned on, the output(V_(out)) of the third switching element TrS (refer to FIG. 4) ischanged to a voltage corresponding to the electrical charge stored inthe capacitor (capacitive element Ca) of the partial detection area PAAcoupled to the detection circuit 48 through the third switching elementTrS, by the electrical charge stored in the capacitor (capacitiveelement Ca) of the partial detection area PAA (period t3). In theexample of FIG. 8, this voltage is reduced from the reset voltage asillustrated in the period t3. Then, after the switch SSW is turned on(high-level period t4 of an SSW signal), the electrical charge stored inthe capacitor (capacitive element Ca) of the partial detection area PAAmoves to a capacitor (capacitive element Cb) of the detection signalamplifier 42 of the detection circuit 48, and the output voltage of thedetection signal amplifier 42 is set to a voltage corresponding to theelectrical charge stored in the capacitive element Cb. At this time, thepotential of an inverting input portion of the detection signalamplifier 42 is set to an imaginary short-circuit potential of theoperational amplifier, and therefore, returns to the reference potential(Vref). The A/D converter 43 reads the output voltage of the detectionsignal amplifier 42. In the example of FIG. 8, waveforms of theselection signals ASW(k), ASW(k+1), . . . corresponding to the signallines SGL of the respective columns are set to be a high level tosequentially turn on the third switching elements TrS, and the sameoperation is sequentially performed. This operation sequentially readsthe electrical charges stored in the capacitors (capacitive elements Ca)of the partial detection areas PAA coupled to the gate line GCL. ASW(k),ASW(k+1), . . . in FIG. 8 are, for example, any of ASW 1 to 6 in FIG. 7.

Specifically, after the period t4 starts in which the switch SSW is on,the electrical charge moves from the capacitor (capacitive element Ca)of the partial detection area PAA to the capacitor (capacitive elementCb) of the detection signal amplifier 42 of the detection circuit 48. Atthis time, the non-inverting input (+) of the detection signal amplifier42 is biased to the reference potential (Vref) (for example, 0.75 [V]).As a result, the output (V_(out)) of the third switching element TrS isalso set to the reference potential (Vref) due to the imaginaryshort-circuit between input ends of the detection signal amplifier 42.The voltage of the capacitive element Cb is set to a voltagecorresponding to the electrical charge stored in the capacitor(capacitive element Ca) of the partial detection area PAA at a locationwhere the third switching element TrS is turned on in response to theselection signal ASW(k). After the output (V_(out)) of the thirdswitching element TrS is set to the reference potential (Vref) due tothe imaginary short-circuit, the output of the detection signalamplifier 42 reaches a capacitance corresponding to the voltage of thecapacitive element Cb, and this output voltage is read by the A/Dconverter 43. The voltage of the capacitive element Cb is, for example,a voltage between two electrodes in a capacitor constituting thecapacitive element Cb.

The period t1 is, for example, 20 [μs]. The period t2 is, for example,60 [μs]. The period t3 is, for example, 44.7 [μs]. The period t4 is, forexample, 0.98 [μs].

Although FIGS. 7 and 8 illustrate the example in which the gate linedrive circuit 15 selects the gate line GCL individually, the number ofthe gate lines GCL to be selected is not limited to this example. Thegate line drive circuit 15 may simultaneously select a predeterminednumber (two or more) of the gate lines GCL and sequentially supply thegate drive signals Vgcl to the gate lines GCL in units of thepredetermined number of the gate lines GCL. The signal line selectioncircuit 16 may also simultaneously couple a predetermined number (two ormore) of the signal lines SGL to one detection circuit 48. Moreover, thegate line drive circuit 15 may skip some of the gate lines GCL and scanthe remaining ones. The dynamic range is, for example, approximately 103when the effective exposure period Pex is approximately 4.3 ms. A highresolution can be achieved by setting the frame rate to approximately4.4 fps (substantially 4.4 fps).

The detection device 1 can detect a fingerprint based on capacitance.Specifically, the capacitive element Ca is used. First, all thecapacitive elements Ca are each charged with a predetermined electricalcharge. Then, a finger Fg touches the detection area AA, and thereby,capacitance corresponding to the asperities of the fingerprint is addedto the capacitive element Ca of each of the cells. Thus, a fingerprintpattern can be generated by allowing the detection signal amplifier 42and the A/D converter 43 to read the capacitance indicated by the outputfrom the capacitive element Ca of each of the cells in the state wherethe finger Fg is in contact with the detection area AA, in the samemanner as the acquisition of the output from each of the partialdetection areas PAA described with reference to FIGS. 7 and 8. Thismethod allows a fingerprint to be detected using a capacitance method. Astructure is preferably employed in which the distance between thecapacitor of the partial detection area PAA and an object to be detectedsuch as a fingerprint is set in a range from 100 μm to 300 μm.

The following describes an operation example of the sensor 10, the firstlight sources 61, and the second light sources 62. FIG. 9 is anexplanatory diagram for explaining a relation between driving of thesensor and lighting operations of the light sources in the detectiondevice.

As illustrated in FIG. 9, during each of the periods t(1) to t(4), thedetection device 1 performs the processing in the reset period Prst, theeffective exposure period Pex{(1), . . . , (M)}, and the reading periodPdet described above. During the reset period Prst and the readingperiod Pdet, the gate line drive circuit 15 sequentially performsscanning from the gate line GCL(1) to the gate line GCL(M).

During the period t(1), the second light sources 62 are on, and thefirst light sources 61 are off. As a result, in the detection device 1,currents flow from the photodiodes PD through the signal lines SGL tothe detection circuit 48 based on the second light L62 emitted from thesecond light sources 62. During the period t(2), the first light sources61 are on, and the second light sources 62 are off. As a result, in thedetection device 1, currents flow from the photodiodes PD through thesignal lines SGL to the detection circuit 48 based on the first lightL61 emitted from the first light sources 61. In the same manner, duringthe period t(3), the second light sources 62 are on, and the first lightsources 61 are off; and during the period t(4), the first light sources61 are on, and the second light sources 62 are off.

In this manner, the first light sources 61 and the second light sources62 are caused to be on in a time-division manner at intervals of theperiod t. This operation outputs the first detection signals detected bythe photodiodes PD based on the first light L61 and the second detectionsignals detected by the photodiodes PD based on the second light L62 tothe detection circuit 48 in a time-division manner. Consequently, thefirst detection signals and the second detection signals are restrainedfrom being output to the detection circuit 48 in a mutually superimposedmanner. As a result, the detection device 1 can well detect the varioustypes of the biological information.

The driving method of the first light sources 61 and the second lightsources 62 can be changed as appropriate. For example, in FIG. 9, thefirst light sources 61 and the second light sources 62 are alternatelycaused to be on at intervals of the period t. However, the drivingmethod is not limited thereto. The first light sources 61 may be turnedon in successive periods t, and then, the second light sources 62 may beturned on in successive periods t. The first light sources 61 and thesecond light sources 62 may be simultaneously turned on in each periodt. FIG. 9 illustrates an example of the full-time control method ofexposure. However, also in the control method of exposure duringscanning time of gate line, the first light sources 61 and the secondlight sources 62 may be alternately driven at intervals of the period tin the same manner as FIG. 9.

FIG. 10 is an explanatory diagram for explaining a relation between thedriving of the sensor and the lighting operations of the light sourcesdifferent from the relation of FIG. 9. In the example illustrated inFIG. 10, the first light sources 61 and the second light sources 62 areon during the effective exposure period Pex, and are off during thereset period Prst and the reading period Pdet. Through these operations,the detection device 1 can reduce power consumption required for thedetection.

The lighting operations are not limited to the example illustrated inFIG. 10. The first light sources 61 and the second light sources 62 maybe continuously turned on over all the periods including the resetperiod Prst, the effective exposure period Pex, and the reading periodPdet. Either the first light sources 61 or the second light sources 62may be on during the effective exposure period Pex, and the first lightsources 61 and the second light sources 62 may be alternately on atintervals of the period t.

FIGS. 11 and 12 are cross sectional views schematically illustrating arelation between the sensor and the first and second light sources ofthe detection device according to the first embodiment. FIGS. 11 and 12illustrate operation examples when relative positional relations betweenthe finger Fg and the sensor 10 differ from each other. As illustratedin FIGS. 11 and 12, the sensor base member 21 has a first curved surfaceSa1 and a second curved surface Sa2 on the opposite side of the firstcurved surface Sa1. The first curved surface Sa1 is curved in a convexmanner in a direction from the second curved surface Sa2 toward thefirst curved surface Sa1. The second curved surface Sa2 is curved in aconcave manner along the surface of the finger Fg. The first curvedsurface Sa1 is provided with the photodiodes PD. The sensor base member21 may be of a light-transmitting film-shaped resin material, or may bea curved glass substrate.

A plurality of first light sources 61-1, 61-2, and 61-3 are providedalong the first curved surface Sa1, and emit the first light L61 indifferent directions. A plurality of second light sources 62-1, 62-2,and 62-3 are provided so as to face the second curved surface Sa2, andemit the second light L62 in different directions. The first lightsource 61-1 and the second light source 62-3 are arranged so as tointerpose the finger Fg therebetween, and emit the first light L61 andthe second light L62 in the opposite directions. In the same manner, thefirst light source 61-2 and the second light source 62-2 are arranged soas to interpose the finger Fg therebetween, and emit the first light L61and the second light L62 in the opposite directions. The first lightsource 61-3 and the second light source 62-1 are arranged so as tointerpose the finger Fg therebetween, and emit the first light L61 andthe second light L62 in the opposite directions.

In the following description, the first light sources 61-1, 61-2, and61-3 will each be referred to as the first light source 61 when theyneed not be distinguished from one another, and the second light sources62-1, 62-2, and 62-3 will each be referred to as the second light source62 when they need not be distinguished from one another.

Although not illustrated in FIGS. 11 and 12, each of the first lightsource base member 51 and the second light source base member 52 has acurved shape along the surface of the finger Fg. Alternatively, onelight source base member may be formed into a ring shape so as tosurround the finger Fg, and the first light sources 61 and the secondlight sources 62 may be provided on the inner circumferential surface ofthe light source base member.

FIG. 13 is a schematic view illustrating an exemplary positionalrelation between the second light source 62, the sensor 10, and a bloodvessel VB in the finger Fg. The second light L62 emitted from the secondlight source 62 (at least one or more of the second light sources 62-1,62-2, and 62-3) is transmitted through the finger Fg and enters thephotodiode PD of each of the partial detection areas PAA. At this time,the transmittance of the second light L62 through the finger Fg changesin accordance with pulsation of the blood vessel VB in the finger Fg.Therefore, the pulse rate can be calculated based on periods of thevariation (amplitude) of the detection signal Vdet during a period oftime longer than or equal to the pulsation period of the blood vesselVB.

In the calculation of the pulse rate based on the period of thevariation (amplitude) of the detection signal Vdet, information forcalculating the pulse rate can continue to be acquired more reliably byperforming the calculation based on the detection signal Vdet havinglarger amplitude.

FIG. 14 is a schematic view illustrating a plurality of positions(positions P1, P2, P3, P4, P5, and P6) of the partial detection areasPAA in the photodiode PD that are exemplarily set when the planardetection area AA formed by the photodiodes PD provided so as to facethe finger Fg is viewed in a plan view. FIG. 15 is a graph illustratingtemporal change examples of the detection signals Vdet acquired at thepositions illustrated in FIG. 14. A line L1 in FIG. 15 indicates atemporal change example of the detection signal Vdet from the partialdetection area PAA at the position P1 of FIG. 14. A line L2 in FIG. 15indicates a temporal change example of the detection signal Vdet fromthe partial detection area PAA at the position P2 of FIG. 14. A line L3in FIG. 15 indicates a temporal change example of the detection signalVdet from the partial detection area PAA at the position P3 of FIG. 14.A line L4 in FIG. 15 indicates a temporal change example of thedetection signal Vdet from the partial detection area PAA at theposition P4 of FIG. 14. A line L5 in FIG. 15 indicates a temporal changeexample of the detection signal Vdet from the partial detection area PAAat the position P5 of FIG. 14. A line L6 in FIG. 15 indicates a temporalchange example of the detection signal Vdet from the partial detectionarea PAA at the position P6 of FIG. 14.

For example, the detection signal Vdet from the partial detection areaPAA of the photodiode PD facing the finger Fg provided at the positionP5 near the center of the tip side of the finger Fg in FIG. 14 exhibitsthe temporal change indicated by the line L5 in FIG. 15. Specifically,the line L5 exhibits amplitude in which rise and fall of the output ofthe detection signal Vdet quantified as, for example, a first peak Max1,a first bottom Min1, a second peak Max2, a second bottom Min2, a thirdpeak Max3, . . . , alternate. The output values of the first peak Max1,the second peak Max2, and the third peak Max3 are larger than the outputvalues of the first bottom Min1 and the second bottom Min2. Thus, afirst peak-down variation Pd1 occurs from the first peak Max1 toward thefirst bottom Min1 on the line L5. A first peak-up variation Pu1 occursfrom the first bottom Min1 toward the second peak Max2 on the line L5. Asecond peak-down variation Pd2 occurs from the second peak Max2 towardthe second bottom Min2 on the line L5. A second peak-up variation Pu2occurs from the second bottom Min2 toward the third peak Max3 on theline L5. In this manner, the line L5 exhibits the variation (amplitude)of the detection signal Vdet that repeats the peak-up variation and thepeak-down variation, including in the ranges not denoted by referencenumerals in FIG. 15. Herein, a set of one peak-up variation and onepeak-down variation that occur consecutively, corresponds to onepulsation that occurs in the blood vessel VB.

In the same manner as the line L5, each of the lines L1, L2, L3, L4, andL6 also exhibits the variation (amplitude) of the detection signal Vdetthat repeats the peak-up variation and the peak-down variation. In thismanner, each of the outputs of the detection signals Vdet from thepartial detection areas PAA provided at the different positions P1, P2,P3, P4, P5, and P6 in the detection area AA exhibits the variationcorresponding to the transmittance of the second light L62 that changesin accordance with the pulsation of the blood vessel VB.

As illustrated in the examples of FIG. 14 and FIG. 15, the degree ofvariation (amplitude) of the detection signal Vdet changes depending onthe position where the partial detection area PAA faces the finger Fg.For example, the degrees of amplitude of the line L1 and the line L6 areclearly smaller than the degree of amplitude of the line L5. Thus, whenthe information representing the variation (amplitude) of the detectionsignal Vdet in accordance with the pulsation occurring in the bloodvessel VB is desired to be continuously acquired more reliably, thepartial detection area PAA provided at the position P5 is considered tobe more preferable than the partial detection areas PAA provided at theposition P1 and the position P6.

As can be seen from the difference in positional relation of the sensor10 with the finger Fg between FIGS. 11 and 12, the sensor 10 may bedisplaced from a living body tissue such as the finger Fg during use.When such a positional shift occurs, the degree of variation (amplitude)of the detection signal Vdet at each of the positions (for example, thepositions P1, . . . , P6) provided with the partial detection areas PAAmay change between times before and after a predetermined time (forexample, a predetermined period Pt in FIG. 16 to be explained later).

Therefore, the output processor 50 of the present embodiment performsprocessing (focus processing) for identifying the partial detection areaPAA in which the degree of variation (amplitude) of the detection signalVdet is larger. Specifically, the output processor 50 acquires thedetection signal Vdet during a predetermined period for each of thepartial detection areas PAA. The output processor 50 identifies thepeak-down variation or the peak-up variation that has the largestdifference between the peak and the bottom from among the peak-downvariations and the peak-up variations that have been generated by thedetection signals Vdet output from the partial detection areas PAAduring the predetermined period. The output processor 50 identifies thepartial detection area PAA that has output the detection signal Vdetthat has generated the identified peak-down variation or peak-upvariation.

The locations where the degree of variation (amplitude) of the detectionsignal Vdet is acquired are not limited to the positions P1, P2, P3, P4,P5, and P6. The output processor 50 may individually acquire the degreesof variation (amplitude) of the detection signals Vdet for all thepartial detection areas PAA provided in the sensor 10 or may extractsome of the partial detection areas PAA by sampling a plurality of thepartial detection areas PAA, and individually acquire the degrees ofvariation (amplitude) of the detection signals Vdet from the extractedparts.

In the present embodiment, the output processor 50 individually acquiresthe degrees of variation (amplitude) of the detection signals Vdet forall the partial detection areas PAA provided in the sensor 10, performsthe focus processing, and outputs data based on the detection signalVdet from the partial detection area PAA identified by the focusprocessing as the pulse wave data. The pulse wave data may be dataincluding information representing the frequency of the amplitudegenerated during the predetermined period, may be data includinginformation representing a value of the pulse rate calculated by theoutput processor 50 based on a predefined calculation expression basedon a relation between the unit time (such as a minute) of the pulse rateand a predetermined period, or may be data including informationrepresenting the change itself of the detection signal Vdet that can bedrawn by, for example, the line L1.

FIG. 16 is a time chart for explaining a relation between thepredetermined period Pt and the output from the partial detection areaPAA identified by focus processing. In the present embodiment, thedetection signal Vdet having the largest degree of variation during thepredetermined period Pt from first timing Ta to second timing Tb isidentified from among the detection signals Vdet acquired from therespective partial detection areas PAA during the predetermined periodPt. Data Ia based on the identified detection signal Vdet is output asthe pulse wave data during the predetermined period Pt from the firsttiming Ta to the second timing Tb. The detection signal Vdet having thelargest degree of variation during the predetermined period Pt from thesecond timing Tb to third timing Tc is identified from among thedetection signals Vdet acquired from the respective partial detectionareas PAA during the predetermined period Pt. Data Ib based on theidentified detection signal Vdet is output as the pulse wave data duringthe predetermined period Pt from the second timing Tb to the thirdtiming Tc. The detection signal Vdet having the largest degree ofvariation during the predetermined period Pt from the third timing Tc tofourth timing Td is identified from among the detection signals Vdetacquired from the respective partial detection areas PAA during a perioduntil the predetermined period Pt. Data Ic based on the identifieddetection signal Vdet is output as the pulse wave data during thepredetermined period Pt from the third timing Tc to the fourth timingTd. In the same manner, the pulse wave data is also output for each ofthe predetermined periods Pt after the fourth timing Td.

The predetermined period Pt is a period including a plurality of timesof output of the detection signal Vdet during which an amplitudewaveform obtained by combining the successive peak-up variation andpeak-down variation is derived one or more times. The predeterminedperiod Pt is set in advance. The predetermined period Pt is, forexample, four seconds, but is not limited thereto and can be changed asappropriate.

FIG. 17 is a flowchart illustrating an exemplary flow of processing foroutputting the pulse wave data in the first embodiment. The outputprocessor 50 acquires the output (detection signal Vdet) of each of theoptical sensors (for example, the photodiodes PD) (Step S1). The outputprocessor 50 repeats the processing at Step S1 until the predeterminedperiod Pt elapses (No at Step S2). After the predetermined period Ptelapses (Yes at Step S2), the output processor 50 acquires the degreesof variation of the outputs (detection signals Vdet) of the respectiveoptical sensors (photodiodes PD) (Step S3). The output processor 50identifies an optical sensor that has produced the output having thelargest degree of variation among the degrees of variation of theoutputs (detection signals Vdet) acquired by the processing at Step S3(Step S4). The output processor 50 employs data based on the output(detection signal Vdet) of the optical sensor identified by theprocessing at Step S4 as the pulse wave data (Step S5). If the operationof the detection device 1 has not ended (No at Step S6), the processingat Step S1 is performed again. If the operation of the detection device1 has ended (Yes at Step S6), the process ends.

Although the above has described the acquisition of the pulse wave databased on the detection signal Vdet having the largest degree ofvariation, the detection signal Vdet having the highest peak value amongthe peak values (Max1, Max2, Max3, . . . ) may be employed instead ofthe detection signal Vdet having the largest degree of variation. Thatis, the pulse wave data may be acquired based on the detection signalVdet having the highest peak value.

As described above, according to the first embodiment, the detectiondevice 1 includes the optical sensors (for example the photodiodes PD)arranged in the detection area AA, the light sources (for example, thefirst light sources 61 and the second light sources 62) for emittinglight that irradiates the object to be detected (for example, the fingerFg) and is detected by the optical sensors, and the processor (forexample, the output processor 50) that performs the processing based onthe outputs from the optical sensors. The processor determines theoptical sensor that has produced the output to be employed from amongthe optical sensors, based on the outputs of the respective opticalsensors obtained at a cycle of a predetermined period (for example, thepredetermined period Pt). With this configuration, even if thepositional relation between the optical sensors and the object to bedetected changes, the optical sensor that has produced the output to beemployed is appropriately determined at the cycle of the predeterminedperiod. Therefore, the output in response to the change in the positioncan be obtained at the cycle of the predetermined period. Consequently,it is possible to deal with the change in the positional relationbetween the optical sensors and the object to be detected.

The processor (for example, the output processor 50) employs the outputof the optical sensor (for example, the photodiode PD) that has producedthe largest output during the predetermined period (for example, thepredetermined period Pt), or that has produced the output having thelargest degree of variation during the predetermined period. Thisprocessing employs the output of the optical sensor that has producedthe largest output during the predetermined period or that has producedthe output having the largest degree of variation during thepredetermined period as the most appropriate output for obtaining thesensor output Vo including the pulse wave data. As a result, theaccuracy of the pulse wave data can be further improved even if thepositional relation between the optical sensors and the object to bedetected changes. Consequently, it is possible to deal with the changein the positional relation between the optical sensors and the object tobe detected.

Second Embodiment

The following describes a second embodiment. With regard to thedescription of the second embodiment, the same components as those ofthe first embodiment will be denoted by the same reference numerals andwill not be described.

In the first embodiment, the optical sensor (photodiode PD) that hasproduced the output (detection signal Vdet) having the largest degree ofvariation is identified, and the data based on the output from theoptical sensor is employed as the pulse wave data. The pulse wave dataof the second embodiment differs from that of the first embodiment inthat the data is based on an output from the group area (group area PAG)including the optical sensor (photodiode PD) that has produced theoutput (detection signal Vdet) having the largest degree of variation.

FIGS. 18 and 19 are schematic diagrams for explaining pulse wave dataacquisition control on a group area PAG basis. Although FIGS. 18 and 19are schematic diagrams obtained by enlarging, for example, the positionP5 of FIG. 14 and the vicinity of the position P5, the presentembodiment is not limited to these diagrams. FIGS. 18 and 19 exemplarilyillustrate a detection area of the sensor 10 in which x×y=6×6 of thegroup areas PAG are arranged in a matrix having a row-columnconfiguration. To distinguish the positions of x×y=6×6 of the groupareas PAG, coordinates x1, x2, x3, x4, x5, and x6 are assigned in thefirst direction Dx, and coordinates y1, y2, y3, y4, y5, and y6 areassigned in the second direction Dy. For example, the group area PAG at(x1,y1) refers to the group area PAG corresponding to a positionrepresented by combining the coordinate x1 with the coordinate y1. InFIGS. 18 and 19, a predetermined number (for example, x×y=6×6) of thepartial detection areas PAA arranged in a matrix having a row-columnconfiguration are exemplarily defined collectively as one group areaPAG.

FIG. 18 illustrates an example in which the blood vessel VB is locatedin a region of the coordinates y2, y3, and y4. Among the partialdetection areas PAA illustrated in FIG. 18, the partial detection areaPAA that produces the output (detection signal Vdet) having the largestdegree of variation is assumed to be located in a position Pmax1 in thegroup area PAG at (x5,y3).

FIG. 19 illustrates an example in which the blood vessel VB is locatedin a region of the coordinates y3, y4, and y5. The difference betweenFIGS. 18 and 19, that is, the difference between the positions of theblood vessel VB is caused by, for example, the positional shift of thesensor 10 with respect to the finger Fg (refer to FIGS. 11 and 12). Whenthe positional shift occurs from the state of FIG. 18 to the state ofFIG. 19, the position of the partial detection area PAA that producesthe output (detection signal Vdet) having the largest degree ofvariation is displaced from the position Pmax1 to a position Pmax2 inthe group area PAG at (x5,y4).

In the first embodiment, the output (detection signal Vdet) from thepartial detection area PAA in the position Pmax1 is employed as theoutput during the predetermined period Pt before the positional shift(refer to FIG. 18), and the output (detection signal Vdet) from thepartial detection area PAA in the position Pmax2 is employed as theoutput during the predetermined period Pt after the positional shift(refer to FIG. 19). In contrast, in the second embodiment, the outputs(detection signals Vdet) from the partial detection areas PAA providedin the group area PAG at (x5,y3) including the partial detection areaPAA in the position Pmax1 are employed as outputs during thepredetermined period Pt before the positional shift (refer to FIG. 18),and the outputs (detection signals Vdet) from the partial detectionareas PAA provided in the group area PAG at (x5,y4) including thepartial detection area PAA in the position Pmax2 are employed as outputsduring the predetermined period Pt after the positional shift (refer toFIG. 19). In this manner, in the second embodiment, the outputs from thegroup area PAG including the partial detection area PAA that producesthe output (detection signal Vdet) having the largest degree ofvariation are employed.

FIG. 20 is an explanatory diagram illustrating examples of averagingprocessing of the outputs from the partial detection areas PAA. In thesecond embodiment, when the outputs (detection signals Vdet) from thepartial detection areas PAA provided in the group area PAG including thepartial detection area PAA that produces the output (detection signalVdet) having the largest degree of variation are employed, the averagingprocessing is performed to average the outputs from the partialdetection areas PAA. In the averaging processing, the outputs (detectionsignals Vdet) of the respective partial detection areas PAA arequantified using analog-to-digital conversion processing to obtainoutput values, the output values of the partial detection areas PAA areadded together, and the sum of the output values is divided by thenumber of the partial detection areas PAA the output values of whichhave been added together.

In FIG. 20, the “output value” row of the tables indicates the outputvalues obtained by quantifying the outputs (detection signals Vdet) fromthe respective partial detection areas PAA. In each of the tables, inorder to distinguish the position of each of the partial detection areasPAA, coordinates xa, xb, and xc are assigned in the first direction Dx,and coordinates ya, yb, yc, yd, ye, yf, and yg are assigned in thesecond direction Dy. That is, the value in one cell of the tableindicates the output value of one of the partial detection areas PAA.The value in each cell is merely exemplary, and does not indicate thatthe output value from each of the partial detection areas PAA is limitedto the value in the cell.

The value in each cell is the same among the tables in the “outputvalues” row of the “without averaging processing” column, the “averagingprocessing example 1 (three)” column, and the “averaging processingexample 2 (five)” column in FIG. 20. While the output value indicated ineach cell of the tables is an output value at certain timing, graphs ofthe output values illustrated in the “graph” row are graphs eachindicating how the output value, which has been obtained a plurality oftimes during a period (for example, the predetermined period Pt)including the certain timing, has changed during the period.

A line La in the graph “without averaging processing” of FIG. 20indicates the temporal change of the output value of each of the partialdetection areas PAA when the output value is employed as it is. A lineLb in the graph “averaging processing example 1 (three)” employs theaverage value of the output values of three of the partial detectionareas PAA continuously arranged in one direction (for example, thesecond direction Dy). As illustrated in the graph “averaging processingexample 1 (three)”, performing the averaging processing reduces theinfluence of noise on the output values, and thus, further clarifies theperiodicity of peaks and bottoms indicated by the temporal change of theoutput values. A line Lc in the graph “averaging processing example 2(five)” employs the average value of the output values of five of thepartial detection areas PAA continuously arranged in the one direction.By increasing the number of the partial detection areas PAA having theoutput values to be averaged, the influence of various types of noise,such as device variations and power supply noise, in the output valuesis further reduced, and thus, the periodicity of peaks and bottomsindicated by the temporal change of the output values is furtherclarified.

In FIG. 20, the number (predetermined number) of the partial detectionareas PAA having the output values to be averaged is merely an examplefor explaining the averaging processing. The present embodiment is notlimited to this example. In the second embodiment, for example, theoutput values of the partial detection areas PAA provided in one of thegroup areas PAG including the partial detection area PAA that producesthe output (detection signal Vdet) having the largest degree ofvariation are averaged, and the averaged value is employed as the outputvalue from the group area PAG. In the second embodiment, the outputvalues of the partial detection areas PAA provided in the one of thegroup areas PAG and the output values of the partial detection areas PAAprovided in a group area PAG near the one of the group areas PAG may beaveraged, and the averaged value may be employed as the output valuefrom the group area PAG. The group area PAG near the one of the groupareas PAG may be, for example, a group area PAG adjacent to the one ofthe group areas PAG along the first direction Dx or the second directionDy, or may be a plurality of group areas PAG arranged continuously tothe one of the group areas PAG along either the first direction Dx orthe second direction Dy.

FIG. 21 is a flowchart illustrating an exemplary flow of processing foroutputting the pulse wave data in the second embodiment. The flow of theprocessing of the second embodiment illustrated in FIG. 21 is the sameas that of the processing of the first embodiment except that theprocessing at Step S5 in the flow of the processing of the firstembodiment illustrated in FIG. 17 is replaced with processing at StepS15.

The output processor 50 performs, as the processing at Step S15, theaveraging processing to average the outputs of the group areas (groupareas PAG) including the optical sensor (photodiode PD of the partialdetection area PAA) identified by the processing at Step S4, andacquires the pulse wave data based on the amplitude indicated by thetemporal change of the output value obtained by the averagingprocessing.

As described above, the second embodiment is the same as the firstembodiment except in the respects otherwise explained.

According to the second embodiment, the detection area AA includes aplurality of group areas (for example, the group areas PAG). Each of thegroup areas includes a plurality of optical sensors (for example, thephotodiodes PD). The output processor 50 employs the output of the grouparea that includes the optical sensor that has produced the largestoutput during the predetermined period (for example, the predeterminedperiod Pt), or that has produced the output having the largest degree ofvariation during the predetermined period. This processing employs theoutput of the group area that includes the optical sensor that hasproduced the largest output during the predetermined period or that hasproduced the output having the largest degree of variation during thepredetermined period as the most appropriate output for obtaining thesensor output Vo including the pulse wave data. As a result, theaccuracy of the pulse wave data can be further improved even if thepositional relation between the optical sensors and the object to bedetected changes. Thus, it is possible to deal with the change in thepositional relation between the optical sensors and the object to bedetected.

The optical sensors (for example, the photodiodes PD) are arranged in amatrix having a row-column configuration in the detection area AA. Theoutput processor 50 performs the averaging processing to average theoutputs of a predetermined number of the optical sensors that are two ormore adjacent optical sensors and are not all the optical sensors, anddetermines, based on the output averaged by the averaging processing,the optical sensor the output of which is to be employed. This operationfurther reduces the influence of the various types of noise in theoutput value, and thus, further clarifies the periodicity of peaks andbottoms indicated by the temporal change of the output values. Thus, theaccuracy of the sensor output Vo such as the pulse wave data can befurther improved. The specific content of the averaging processing isnot limited to this processing and can be changed as appropriate. Forexample, at least one of the gate lines GCL and a plurality of thesignal lines SGL, or a plurality of the gate lines GCL and at least oneof the signal lines SGL may be handled collectively, and the outputsfrom the adjacent partial detection areas PAA may be simultaneouslyread.

Third Embodiment

The following describes a third embodiment. With regard to thedescription of the third embodiment, the same components as those of thefirst embodiment or the second embodiment will be denoted by the samereference numerals and will not be described.

In the third embodiment, a fingerprint detection is performed bygenerating the fingerprint pattern of a finger Fg as described withreference to FIGS. 11 and 12. The fingerprint detection is performed atintervals of the predetermined period Pt. The output processor 50calculates an amount of positional shift of the photodiode PD withrespect to the finger Fg based on a difference in the positionalrelation between the position of the fingerprint pattern detected first(initial fingerprint pattern) and the position of the fingerprintpattern detected thereafter. The output processor 50 corrects thepositional shift of the optical sensor (partial detection area PAA) tobe handled as an output to be employed, based on the calculated amountof shift.

As a specific method for detecting the fingerprint, both of thefollowing methods can be used: a method in which a fingerprint patternis generated using the sensor 10 as an optical sensor based on thedetection of the light from at least either the first light sources 61or the second light sources 62, and a method in which the asperities ofthe fingerprint are recognized by a capacitive sensor using thecapacitance of the capacitive element Ca.

In the third embodiment, as an example, the first light L61 has awavelength from 360 nm to 800 nm, for example, at approximately 500 nm,and the second light L62 has a wavelength from 800 nm to 930 nm, forexample, at approximately 850 nm. That is, the wavelength of the secondlight L62 is longer than the wavelength of the first light L61. In thiscase, the first light L61 is visible light, and the second light L62 isinfrared light.

When light having one of the two wavelengths of the first light L61 andthe second light L62 is used to detect a fingerprint, and light havingthe other of the two wavelengths is used to detect a blood vessel and apulse wave pattern, the first light L61 is used for detecting thefingerprint, and the second light L62 is used for detecting the bloodvessel and the pulse wave pattern. Light having one wavelength of thesecond light L62 may be used to detect both the fingerprint and theblood vessel.

FIG. 22 is a flowchart illustrating an exemplary flow of processing foroutputting the pulse wave data in the third embodiment and a fourthembodiment (to be described later). In the third embodiment and thefourth embodiment (to be described later), initial processing is firstperformed (Step S21). Then, positional shift handling processing isperformed (Step S22). The processing at Step S22 is repeated until theoperation of the detection device 1 ends (No at Step S23). After theoperation of the detection device 1 ends (Yes at Step S23), the processends.

FIG. 23 is a flowchart illustrating an exemplary flow of the initialprocessing of FIG. 22. The initial processing is the same as theprocessing described with reference to the flowchart illustrated in FIG.21 except that the processing at Step S6 of the flowchart illustrated inFIG. 21 is omitted. The return after the processing at Step S15 of FIG.23 indicates that the processing (initial processing) at Step S21illustrated in FIG. 22 ends, and the processing (positional shifthandling processing) at Step S22 as the next processing is performed.

FIG. 24 is a flowchart illustrating an exemplary flow of the positionalshift handling processing of FIG. 22 in the third embodiment. Thefingerprint pattern is first acquired (Step S31). The acquisition of thefingerprint pattern at Step S31 is performed based on, for example, theoutput of each of the optical sensors (photodiodes PD) during theinitial processing. Although the fingerprint pattern is generated basedon the output at any desired timing during the initial processing, thetiming is set in advance (for example, the initial time).

The output processor 50 acquires the output (detection signal Vdet) ofeach of the optical sensors (photodiodes PD) (Step S32). The outputprocessor 50 repeats the processing at Step S32 until the predeterminedperiod Pt elapses (No at Step S33). After the predetermined period Ptelapses (Yes at Step S33), the fingerprint pattern is acquired (StepS34). The acquisition of the fingerprint pattern at Step S34 isperformed based on, for example, the latest output of each of theoptical sensors (photodiodes PD). However, the output is not limitedthereto and only needs to be the output of each of the optical sensors(photodiodes PD) within a period that starts before not longer than thepredetermined period Pt.

The output processor 50 calculates the amount of shift of the latestfingerprint pattern from the initial fingerprint pattern (Step S35).Specifically, the output processor 50 compares, as the processing atStep S35, the positional relation between the fingerprint patternacquired by the processing at Step S31 and the partial detection areasPAA with the positional relation between the fingerprint patternacquired by the processing at Step S34 and the partial detection areasPAA. The output processor 50 determines whether the position of apartial detection area PAA in which the asperities determined to be thesame fingerprint pattern were detected has shifted, based on collationprocessing such as detection of feature points included in thefingerprint pattern. If the position has shifted, the output processor50 quantifies the amount of the shift as amounts of shifts of thepartial detection area PAA in the first direction Dx and the seconddirection Dy.

The output processor 50 identifies the optical sensor (photodiode PD)located in the position shifted by the amount of shift calculated by theprocessing at Step S35 from the position of the optical sensoridentified by the processing at Step S4 in the initial processing as theoptical sensor (photodiode PD) that has produced the output having thelargest degree of variation (Step S36). The output processor 50 acquiresthe pulse wave data from the amplitude of the output value obtained byaveraging the outputs of the group area (group area PAG) including theoptical sensor identified by the processing at Step S36 (Step S37). Theprocessing at Step S37 is the same as the processing at Step S15 exceptthat the reference for determining the group area is changed from theoptical sensor identified by the processing at Step S4 to the opticalsensor identified by the processing at Step S36. The return after theprocessing at Step S37 of FIG. 24 and FIG. 26 to be explained laterindicates that the processing (positional shift handling processing) atStep S22 illustrated in FIG. 22 ends, and the processing at Step S23 asthe next processing is performed.

In the description with reference to FIGS. 22, 23, and 24, thefingerprint detection is performed at the time of pulse wavemeasurement, that is, at every interval of the predetermined period Ptin which the variation (amplitude) of the output for acquiring the pulsewave occurs. However, the present embodiment is not limited thereto. Thefingerprint detection may be performed during a full operation period(to be described later), and not performed in the other periods, so thatthe fingerprint detection is performed once for a plurality of times ofpulse wave measurement (skipped fingerprint measurement). As describedabove, the third embodiment is the same as the second embodiment exceptin the respects otherwise explained.

According to the third embodiment, the detection area AA faces thefinger Fg (refer to FIGS. 11 and 12). The output processor 50 determinesthe optical sensor that has produced the output to be employed fromamong the optical sensors (for example, the photodiodes PD) based on thefingerprint pattern generated based on the output of each of the partialdetection areas PAA. With this configuration, even if the positionalrelation between the optical sensors and the finger Fg changes, theoutput to be employed is determined based on the positional shift of thedetected fingerprint pattern. Therefore, the output in response to thechange in the position can be obtained at the cycle of the predeterminedperiod. Thus, it is possible to deal with the change in the positionalrelation between the optical sensors and the finger Fg.

Modification of Third Embodiment

The following describes a modification in which the processing from StepS35 to Step S37 in the third embodiment is replaced with otherprocessing. Specifically, in the modification, the process branchesbased on whether the latest fingerprint pattern (refer to Step S34) hasshifted from the initial fingerprint pattern (refer to Step S31).

FIG. 25 is a flowchart illustrating an exemplary flow of the positionalshift handling processing of FIG. 22 in the modification of the thirdembodiment. The processing from Step S31 to Step S34 is the same as theprocessing described with reference to FIG. 24.

The output processor 50 determines whether the latest fingerprintpattern has shifted from the initial fingerprint pattern (Step S45).Specifically, the output processor 50 compares, as the processing atStep S45, the positional relation between the fingerprint patternacquired by the processing at Step S31 and the partial detection areasPAA with the positional relation between the fingerprint patternacquired by the processing at Step S34 and the partial detection areasPAA. The output processor 50 determines whether the position of apartial detection area PAA in which the asperities determined to be thesame fingerprint pattern were detected has shifted, based on thecollation processing such as the detection of the feature pointsincluded in the fingerprint pattern.

If the processing at Step S45 determines that the shift has occurred(Yes at Step S46), the output processor 50 sequentially performs theprocessing at Step S3, the processing at Step S4, and the processing atStep S15. If, in contrast, the processing at Step S45 determines thatthe shift has not occurred (No at Step S46), the output processor 50acquires the pulse wave data from the amplitude of the output valueobtained by averaging the outputs of the group area (group area PAG)including the optical sensor (photodiode PD) that is determined to haveproduced the output having the largest degree of variation by theprocessing at Step S4 in the initial processing (Step S47). The returnafter the processing at Step S15 of FIG. 25 and FIG. 27 to be explainedlater and after the processing at Step S47 indicates that the processing(positional shift handling processing) at Step S22 illustrated in FIG.22 ends, and the processing at Step S23 as the next processing isperformed.

As described above, the modification of the third embodiment is the sameas the third embodiment except in the respects otherwise explained.

Fourth Embodiment

The following describes the fourth embodiment. With regard to thedescription of the fourth embodiment, the same components as those ofthe first embodiment, the second embodiment, and the third embodimentwill be denoted by the same reference numerals and will not bedescribed.

In the third embodiment, the fingerprint pattern is used in thepositional shift handling processing. The fourth embodiment differs fromthe third embodiment in that the vascular pattern generated based on theshape of the blood vessel VB facing the detection area AA is used in thepositional shift handling processing. Specifically, in the fourthembodiment, the initial processing in the flow of processing describedwith reference to FIG. 22 is the same as that of the third embodiment,and the positional shift handling processing partially differs from thatof the third embodiment.

FIG. 26 is a flowchart illustrating an exemplary flow of the positionalshift handling processing of FIG. 22 in the fourth embodiment. In thefourth embodiment, the acquisition of the vascular pattern is performedas processing at Step S51 instead of the processing at Step S31 in thethird embodiment. The acquisition of the vascular pattern at Step S51 isperformed based on, for example, the output of each of the opticalsensors (photodiodes PD) during the initial processing. Although thevascular pattern is generated based on the output at any desired timingduring the initial processing, the timing is set in advance (forexample, the initial time).

In the fourth embodiment, the acquisition of the vascular pattern isperformed as processing at Step S54 instead of the processing at StepS34 in the third embodiment. The acquisition of the vascular pattern atStep S54 is performed based on, for example, the latest output of eachof the optical sensors (photodiodes PD). However, the output is notlimited thereto and only needs to be the output of each of the opticalsensors (photodiodes PD) within a period that starts before not longerthan the predetermined period Pt.

In the fourth embodiment, processing at Step S55 is performed instead ofthe processing at Step S35 in the third embodiment. In the processing atStep S55, the output processor 50 calculates the amount of shift of thelatest vascular pattern with respect to the initial vascular pattern.Specifically, the output processor 50 compares the positional relationbetween the vascular pattern acquired by the processing at Step S51 andthe partial detection areas PAA with the positional relation between thevascular pattern acquired by the processing at Step S54 and the partialdetection areas PAA. The output processor 50 performs processing todetermine whether the position of a partial detection area PAA in whichthe same vascular pattern was detected has shifted, based on thecollation processing such as the detection of feature points included inthe vascular pattern. If the position has shifted, the output processor50 quantifies the amount of the shift as amounts of shifts of thepartial detection area PAA in the first direction Dx and the seconddirection Dy.

As described above, the fourth embodiment is the same as the thirdembodiment except in the respects otherwise explained. In the fourthembodiment, the vascular pattern corresponding to the blood vessel VB isemployed. The type of the blood vessel VB may be any blood vessel, suchas an artery, a vein, or other.

According to the fourth embodiment, the detection area AA faces theliving body tissue (for example, the finger Fg or a wrist Wr, which willbe described later) including therein a blood vessel (for example, theblood vessel VB). The output processor 50 determines the optical sensorthat has produced the output to be employed from among the opticalsensors based on the vascular pattern (for example, the pattern of theblood vessel VB) generated based on the outputs of the respectiveoptical sensors (for example, the photodiodes PD). With thisconfiguration, even if the positional relation between the opticalsensors and the living body tissue changes, the output to be employed isdetermined based on the positional shift of the detected vascularpattern. Therefore, the output in response to the change in the positioncan be obtained at the cycle of the predetermined period. Thus, it ispossible to deal with the change in the positional relation between theoptical sensors and the living body tissue.

Modification of Fourth Embodiment

The following describes a modification in which the processing at StepS55, Step S36, and Step S37 in the fourth embodiment is replaced withother processing. Specifically, in the same manner as the replacement ofthe fingerprint pattern in the third embodiment with the vascularpattern in the fourth embodiment, the fingerprint pattern in themodification of the third embodiment is replaced with the vascularpattern in the modification of the fourth embodiment. Specifically, inthe modification of the fourth embodiment, the process branches based onwhether the latest vascular pattern (refer to Step S54) has shifted fromthe initial vascular pattern (refer to Step S51).

FIG. 27 is a flowchart illustrating an exemplary flow of the positionalshift handling processing of FIG. 22 in the modification of the fourthembodiment. The processing from Step S51 to Step S54 in the modificationof the fourth embodiment is the same as that of the fourth embodiment(refer to FIG. 26).

The output processor 50 determines whether the latest vascular patternhas shifted from the initial vascular pattern (Step S65). Specifically,the output processor 50 compares, as the processing at Step S65, thepositional relation between the vascular pattern acquired by theprocessing at Step S51 and the partial detection areas PAA with thepositional relation between the vascular pattern acquired by theprocessing at Step S54 and the partial detection areas PAA. The outputprocessor 50 determines whether the position of the partial detectionarea PAA in which the same vascular pattern was detected has shifted,based on the collation processing such as the detection of the featurepoints included in the vascular pattern.

If the processing at Step S65 determines that the shift has occurred(Yes at Step S46), the output processor 50 sequentially performs theprocessing at Step S3, the processing at Step S4, and the processing atStep S15. If, in contrast, the processing at Step S65 determines thatthe shift has not occurred (No at Step S46), the output processor 50performs the processing at Step S47.

As described above, the modification of the fourth embodiment is thesame as the fourth embodiment except in the respects otherwiseexplained.

In the above description, the method has been described for repeatedlyacquiring the outputs from all the optical sensors (photodiodes PD)during the predetermined period Pt. However, the operation control ofthe optical sensors is not limited thereto. The detection controller 11may generate the full operation period for operating all the opticalsensors (photodiodes PD) at a cycle of a predetermined period, and mayoperate, during a period other than the full operation period, some ofthe optical sensors including the optical sensor that has produced thelargest output during the full operation period or that has produced theoutput having the largest degree of variation during the full operationperiod. In this case, as indicated by a dashed line in FIG. 2, theoutput processor 50 feeds information back to detection controller 11,which indicates the position of an optical sensor that has produced thelargest output during the full operation period or that has produced theoutput having the largest degree of variation during the full operationperiod, or indicates the group area PAG including the optical sensor.Based on the information fed back from the output processor 50, thedetection controller 11 identifies and operates some of the opticalsensors including the optical sensor that has produced the largestoutput during the full operation period or that has produced the outputhaving the largest degree of variation during the full operation period.

For example, a full operation period Ba is set within the predeterminedperiod Pt from the first timing Ta to the second timing Tb in FIG. 16,the full operation period Ba being a period in which all the partialdetection areas PAA are operated. The detection signal Vdet having thelargest degree of variation during the full operation period Ba isidentified; and the partial detection area PAA provided in an area wherethe partial detection area PAA provided in a group area PAG includingthe partial detection area PAA that has output the identified detectionsignal Vdet is included, or the group area PAG is included, and wherenot all the partial detection areas PAA are included, is determined asthe partial detection area PAA that operates during a period Aa otherthan the full operation period. The detection signal Vdet having thelargest degree of variation during the full operation period Ba and theperiod Aa is identified, and data based on the output from the grouparea PAG including the partial detection area PAA that has output theidentified detection signal Vdet having the largest degree of variationis output as the pulse wave data. The pulse wave data based on theoutput from the group area PAG including the partial detection area PAAthat has output the detection signal Vdet having the largest degree ofvariation refers to, for example, the pulse wave data obtained throughthe averaging processing. The relation between a full operation periodBb and a period Ab set in the predetermined period Pt from the secondtiming Tb to the third timing Tc is the same as that in the operationcontrol in the full operation period Ba and the period Aa. The relationbetween a full operation period Bc and a period Ac set in thepredetermined period Pt from the third timing Tc to the fourth timing Tdis also the same as that in the operation control in the full operationperiod Ba and the period Aa. The operation control in the full operationperiod and the period other than the full operation period set in thepredetermined period Pt thereafter is the same as the operation controlin the full operation period Ba and the period Aa.

The area where the group area PAG including the partial detection areaPAA that has output the detection signal Vdet having the largest degreeof variation during the full operation period (for example, the fulloperation period Ba, Bb, or Bc) is included and where not all thepartial detection areas PAA are included, refers to an area including aplurality of group areas PAG located in the same position in the firstdirection Dx or the second direction Dy as in the group area PAG, forexample. The area is not limited thereto and may be changed asappropriate.

As described above, the detection controller 11 for controlling theoperation of the optical sensors (for example, the photodiodes PD)generates the full operation period (for example, the full operationperiod Ba, Bb, or Bc) in which all the optical sensors are operated atthe cycle of the predetermined period (for example, the predeterminedperiod Pt). During the period (for example, the period Aa, Ab, or Ac)other than the full operation period, the detection controller 11operates some of the optical sensors including the optical sensor thathas produced the largest output during the full operation period or thathas produced the output having the largest degree of variation duringthe full operation period. This configuration can reduce the number ofthe optical sensors that operate during the period other than the fulloperation period. Thus, the refresh rate of the optical sensors operatedduring the period other than the full operation period can be increasedmore easily.

The detection signals Vdet to be averaged are not limited to thedetection signals Vdet from the partial detection areas PAA provided inone of the group areas PAG. For example, the detection signal Vdet ofone partial detection area PAA that has output the detection signal Vdethaving the largest degree of variation and the detection signal Vdet ofanother partial detection area PAA having a positional relationsatisfying a predetermined condition with the one partial detection areaPAA may be averaged. Examples of the predetermined condition include acondition that at least one of the position in the first direction Dxand the position in the second direction Dy of the partial detectionarea PAA is the same as the position of the one partial detection areaPAA that has output the detection signal Vdet having the largest degreeof variation, a condition that the number of other partial detectionareas PAA interposed between the one partial detection areas PAA and theother partial detection areas PAA is within a predetermined number, anda condition that a combination of these conditions is satisfied. Thevalue of the predetermined number is preferably sufficiently smallerthan the number of the partial detection areas PAA arranged in the firstdirection Dx and the number of the partial detection areas PAA arrangedin the second direction Dy.

The averaging processing is not essential. For example, for the grouparea PAG including the partial detection area PAA that has output thedetection signal Vdet having the largest degree of variation during thefull operation period (for example, the full operation period Ba, Bb, orBc), at least either the gate lines GCL or the signal lines SGL in thegroup area PAG may be collectively driven during the period (forexample, the period Aa, Ab, or Ac) other than the full operation period,and the detection signals Vdet from the partial detection areas PAAprovided in the group area PAG may be integrated.

The size and characteristics of the partial detection areas PAA need notbe uniform. For example, a plurality of types of the photodiodes PDhaving different sensitivity may be alternately arranged to increase thedynamic range of the entire partial detection areas PAA.

The specific form of the detection device 1 is not limited to the formdescribed with reference to FIGS. 11 to 13. FIG. 28 is a schematic viewillustrating a main configuration example of a detection device lA in aform wearable on the wrist Wr. FIG. 29 is a schematic diagramillustrating an example of the detection of the blood vessel VB by thedetection device lA illustrated in FIG. 28. As illustrated in FIG. 28,the sensor base member 21 of the detection device lA has flexibility tobe deformable into an annular shape surrounding the wrist Wr. Thephotodiodes PD, the first light sources 61, and the second light sources62 are arranged in an arc shape along the annular sensor base member 21.

The sensor 10 need not directly contact the living body tissue. FIG. 30is a configuration example in which a lens Op is provided between thefinger Fg and the sensor 10. As illustrated in FIG. 30, the lens Op maybe provided in a position that faces a light source 60 with the livingbody tissue (for example, the finger Fg) interposed therebetween, and isinterposed between the living body tissue and the sensor 10. The lightsource 60 includes at least either the first light sources 61 or thesecond light sources 62. The lens Op is, for example, an optical lensthat condenses light traveling from the light source 60 toward thesensor 10.

The detection device 1 and the detection device lA may be furtherprovided with a component, as a sensor different from a photodiode (PD),capable of detecting, for example, the fingerprint using the capacitancemethod.

FIG. 31 is a schematic diagram illustrating a main configuration exampleof a mutual capacitive sensor 130. The sensor 130 includes a firstsubstrate 102 and a second substrate 103 arranged so as to face eachother. The first substrate 102 and the second substrate 103 extend alonga plane (XY plane) orthogonal to the facing direction (Z-direction). TheXY plane need not be a fixed immovable plane. The first directionDx-second direction Dy plane is allowed to be displaced as well as beingallowed to be, for example, curved depending on the flexibility of thesensor base member 21. In the following description, for ease ofunderstanding, “X-direction” and “Y-direction” denote two directionsalong the plane (XY plane) orthogonal to the Z-direction of FIG. 31. TheX-direction is orthogonal to the Y-direction.

The first substrate 102 is provided with a plurality of first electrodesTX that have a longitudinal direction along the X-direction and arearranged along the Y-direction. The second substrate 103 is providedwith a plurality of second electrodes Rx that have a longitudinaldirection along the Y-direction and are arranged in the X-direction. Thefirst electrodes TX face the second electrodes Rx in the Z-direction ina non-contact state. The sensor 130 is provided so as to come intoproximity to or contact with an external object such as the finger Fg onthe second substrate 103 side.

When scanning Scan is performed to sequentially apply drive pulses tothe first electrodes TX, capacitance is generated between the secondelectrodes Rx and the first electrodes TX to which the drive pulses areapplied. If, for example, the finger Fg comes into proximity to orcontact with the second electrodes Rx, the capacitance varies. Forexample, the fingerprint or the like can be detected by acquiring thepresence or absence of variation in the capacitance and the degree ofthe variation in the capacitance, as a detection signal Vdetl from thesecond electrodes Rx.

The position of the sensor 130 is associated with the position of thesensor 10 in advance. While the sensor 130 is disposed in, for example,the detection device 1 so as to face the finger Fg with, for example,the sensor 10 interposed therebetween, the arrangement is not limitedthereto. For example, the first electrodes TX and the second electrodesRx may be transparent electrodes of, for example, indium tin oxide (ITO)and may be arranged on the finger Fg side of the sensor 10. The firstelectrodes TX and the second electrodes Rx may be individually driven toserve as a self-capacitive sensor.

FIG. 32 is a schematic diagram illustrating a main configuration exampleof a self-capacitive sensor 210. The sensor 210 includes a plurality ofelectrodes 220. The electrodes 220 are arranged, for example, in amatrix having a row-column configuration. The self-capacitance held ineach of the electrodes 220 varies when, for example, the finger Fg comesinto proximity to or contact with the electrode 220. A controller 240coupled to the electrodes 220 through wiring 230 is a circuit thatdetects the presence or absence of variation in the self-capacitance andthe degree of the variation in the self-capacitance.

The position of the sensor 210 is associated with the position of thesensor 10 in advance. While the sensor 210 is disposed in, for example,the detection device 1 so as to face the finger Fg with, for example,the sensor 10 interposed therebetween, the arrangement is not limitedthereto. For example, the electrodes 220 may be transparent electrodesof, for example, indium tin oxide (ITO), and may be arranged on thefinger Fg side of the sensor 10.

The detection device 1 can be mounted on various products supposed to bein contact with or in proximity to the living body tissue. Mountingexamples of the detection device 1 will be described with reference toFIGS. 33, 34, and 35.

FIG. 33 is a diagram illustrating an arrangement example of the sensor10 of the detection device 1 mounted on a bandanna Ke. FIG. 34 is adiagram illustrating an arrangement example of the sensor 10 of thedetection device 1 mounted on clothes TS. FIG. 35 is a diagramillustrating an arrangement example of the sensor 10 of the detectiondevice 1 mounted on an adhesive sheet PS. For example, the detectiondevice 1 may be incorporated into a product, such as the bandanna Ke ofFIG. 33, the clothes TS of FIG. 34, or the adhesive sheet PS of FIG. 35,that is operated to contact the living body tissue. In this case, atleast the sensor 10 is preferably provided at a position expected tocontact the living body tissue when the product is used. Although notillustrated, the light sources such as the first light sources 61 andthe second light sources 62 are preferably arranged taking into accountthe positional relation between the sensor 10 and the living bodytissue. The products are not limited to the bandanna Ke, the clothes TS,and the adhesive sheet PS. The detection device 1 can be incorporatedinto any product expected to contact the living body tissue when theproduct is in use. The adhesive sheet PS is a sheet-like productprovided with adhesiveness, such as external analgesic andanti-inflammatory sheets.

In each embodiment, the case has been described where the gate linedrive circuit 15 performs the time-division selective driving ofsequentially supplying the gate drive signals Vgcl to the gate linesGCL. However, the driving method is not limited to this case. The sensor10 may perform code division selection driving (hereinafter, called“code division multiplexing (CDM) driving”) to perform the detection.Since the CDM driving and a drive circuit thereof are described inJapanese Patent Application No. 2018-005178 (JP-A-2018-005178), what isdescribed in JP-A-2018-005178 is included in each embodiment and themodifications (embodiments), and the description will not be omittedherein.

The gate lines GCL preferably extend along a general direction of bloodflow. Specifically, the gate lines GCL in the sensor 10 extending alongan arc along the annular sensor base member 21 wound around the fingerFg or the wrist Wr preferably extend along the central axis of theannulus.

Although the preferred embodiments of the present invention have beendescribed above, the present invention is not limited to the embodimentsdescribed above. The content disclosed in the embodiments is merely anexample, and can be variously modified within the scope not departingfrom the gist of the present invention. Any modifications appropriatelymade within the scope not departing from the gist of the presentinvention also naturally belong to the technical scope of the presentinvention.

What is claimed is:
 1. A detection device comprising: a photodiode; anda thin-film transistor coupled to the photodiode, wherein the thin-filmtransistor comprises: a semiconductor layer between a light-blockinglayer and the photodiode; and an electrode layer between thesemiconductor layer and the photodiode, the electric layer includes asource electrode and a drain electrode of the thin-film transistor, andwherein the source electrode extends to a position facing thelight-blocking layer with the semiconductor layer interposedtherebetween.
 2. The detection device according to claim 1, wherein thephotodiode comprises: an organic material having a photovoltaic effect;a cathode electrode provided on a thin-film transistor side of theorganic material; and an anode electrode provided on an opposite side ofthe organic material from the cathode electrode, and wherein a layer ofthe organic material and a layer of the anode electrode are continuousalong a detection surface over the respective cathode electrodes of aplurality of the photodiodes PD arranged along the detection surface. 3.The detection device according to claim 1, wherein the thin-filmtransistor comprises two gate electrodes formed between the sourceelectrode and the semiconductor layer.